21297910440 has 32 divisors (see below), whose sum is σ = 63893731680. Its totient is φ = 5679442752.

The previous prime is 21297910429. The next prime is 21297910441. The reversal of 21297910440 is 4401979212.

It is a super-2 number, since 2×21297910440² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21297910441) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 88741174 + ... + 88741413.

It is an arithmetic number, because the mean of its divisors is an integer number (1996679115).

Almost surely, 2^21297910440 is an apocalyptic number.

21297910440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21297910440 is an abundant number, since it is smaller than the sum of its proper divisors (42595821240).

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

21297910440 is a wasteful number, since it uses less digits than its factorization.

21297910440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177482601 (or 177482597 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 39.

The spelling of 21297910440 in words is "twenty-one billion, two hundred ninety-seven million, nine hundred ten thousand, four hundred forty".