21020252437440 has 672 divisors, whose sum is σ = 74985750927360. Its totient is φ = 5401047859200.

The previous prime is 21020252437421. The next prime is 21020252437447. The reversal of 21020252437440 is 4473425202012.

21020252437440 is a `hidden beast` number, since 2 + 1 + 0 + 20 + 2 + 524 + 3 + 74 + 40 = 666.

It is a super-2 number, since 2×21020252437440² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 21020252437395 and 21020252437404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020252437447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3434117580 + ... + 3434123700.

It is an arithmetic number, because the mean of its divisors is an integer number (111585938880).

Almost surely, 2^{21020252437440} is an apocalyptic number.

21020252437440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020252437440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37492875463680).

21020252437440 is an abundant number, since it is smaller than the sum of its proper divisors (53965498489920).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21020252437440 is a wasteful number, since it uses less digits than its factorization.

21020252437440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6541 (or 6528 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 36.

Adding to 21020252437440 its reverse (4473425202012), we get a palindrome (25493677639452).

The spelling of 21020252437440 in words is "twenty-one trillion, twenty billion, two hundred fifty-two million, four hundred thirty-seven thousand, four hundred forty".