21118957440 has 512 divisors, whose sum is σ = 79902720000. Its totient is φ = 4644642816.

The previous prime is 21118957439. The next prime is 21118957459. The reversal of 21118957440 is 4475981112.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a junction number, because it is equal to n+sod(n) for n = 21118957392 and 21118957401.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 42322311 + ... + 42322809.

It is an arithmetic number, because the mean of its divisors is an integer number (156060000).

Almost surely, 2^21118957440 is an apocalyptic number.

21118957440 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 21118957440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39951360000).

21118957440 is an abundant number, since it is smaller than the sum of its proper divisors (58783762560).

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

21118957440 is a wasteful number, since it uses less digits than its factorization.

21118957440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642 (or 630 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 42.

The spelling of 21118957440 in words is "twenty-one billion, one hundred eighteen million, nine hundred fifty-seven thousand, four hundred forty".