21657963 has 8 divisors (see below), whose sum is σ = 29581776. Its totient is φ = 14086400.

The previous prime is 21657959. The next prime is 21657971. The reversal of 21657963 is 36975612.

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

It is a cyclic number.

It is not a de Polignac number, because 21657963 - 2² = 21657959 is a prime.

It is a super-2 number, since 2×21657963² = 938134722618738, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21657943) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87918 + ... + 88163.

It is an arithmetic number, because the mean of its divisors is an integer number (3697722).

Almost surely, 2^21657963 is an apocalyptic number.

21657963 is a deficient number, since it is larger than the sum of its proper divisors (7923813).

21657963 is a wasteful number, since it uses less digits than its factorization.

21657963 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 176125.

The product of its digits is 68040, while the sum is 39.

The square root of 21657963 is about 4653.8116635721. The cubic root of 21657963 is about 278.7442190145.

The spelling of 21657963 in words is "twenty-one million, six hundred fifty-seven thousand, nine hundred sixty-three".