21369746520 has 96 divisors (see below), whose sum is σ = 69699165120. Its totient is φ = 5678292480.

The previous prime is 21369746483. The next prime is 21369746527. The reversal of 21369746520 is 2564796312.

21369746520 is a `hidden beast` number, since 2 + 1 + 36 + 97 + 4 + 6 + 520 = 666.

It is a super-3 number, since 3×21369746520³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21369746527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4464 + ... + 206783.

It is an arithmetic number, because the mean of its divisors is an integer number (726032970).

Almost surely, 2^21369746520 is an apocalyptic number.

21369746520 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 21369746520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34849582560).

21369746520 is an abundant number, since it is smaller than the sum of its proper divisors (48329418600).

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

21369746520 is a wasteful number, since it uses less digits than its factorization.

21369746520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211545 (or 211538 counting only the distinct ones).

The product of its (nonzero) digits is 544320, while the sum is 45.

The spelling of 21369746520 in words is "twenty-one billion, three hundred sixty-nine million, seven hundred forty-six thousand, five hundred twenty".