21657112394 has 8 divisors (see below), whose sum is σ = 33363659748. Its totient is φ = 10535892480.

The previous prime is 21657112339. The next prime is 21657112397. The reversal of 21657112394 is 49321175612.

It can be written as a sum of positive squares in 2 ways, for example, as 16880505625 + 4776606769 = 129925^2 + 69113^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×21657112394² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21657112397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146331767 + ... + 146331914.

Almost surely, 2^21657112394 is an apocalyptic number.

21657112394 is a deficient number, since it is larger than the sum of its proper divisors (11706547354).

21657112394 is a wasteful number, since it uses less digits than its factorization.

21657112394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 292663720.

The product of its digits is 90720, while the sum is 41.

The spelling of 21657112394 in words is "twenty-one billion, six hundred fifty-seven million, one hundred twelve thousand, three hundred ninety-four".