21351243915 has 12 divisors (see below), whose sum is σ = 37008822864. Its totient is φ = 11387330064.

The previous prime is 21351243883. The next prime is 21351243941. The reversal of 21351243915 is 51934215312.

It is a happy number.

21351243915 is a `hidden beast` number, since 2 + 13 + 512 + 43 + 91 + 5 = 666.

It is not a de Polignac number, because 21351243915 - 2⁵ = 21351243883 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21351243915.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 237235999 + ... + 237236088.

It is an arithmetic number, because the mean of its divisors is an integer number (3084068572).

Almost surely, 2^21351243915 is an apocalyptic number.

21351243915 is a deficient number, since it is larger than the sum of its proper divisors (15657578949).

21351243915 is a wasteful number, since it uses less digits than its factorization.

21351243915 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474472098 (or 474472095 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The spelling of 21351243915 in words is "twenty-one billion, three hundred fifty-one million, two hundred forty-three thousand, nine hundred fifteen".