21368457 has 12 divisors (see below), whose sum is σ = 33671664. Its totient is φ = 12950520.

The previous prime is 21368453. The next prime is 21368461. The reversal of 21368457 is 75486312.

It is an interprime number because it is at equal distance from previous prime (21368453) and next prime (21368461).

It is not a de Polignac number, because 21368457 - 2² = 21368453 is a prime.

It is a super-2 number, since 2×21368457² = 913221909121698, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21368453) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 107823 + ... + 108020.

It is an arithmetic number, because the mean of its divisors is an integer number (2805972).

Almost surely, 2^21368457 is an apocalyptic number.

It is an amenable number.

21368457 is a deficient number, since it is larger than the sum of its proper divisors (12303207).

21368457 is a wasteful number, since it uses less digits than its factorization.

21368457 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215860 (or 215857 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21368457 is about 4622.6028382287. The cubic root of 21368457 is about 277.4966349726.

The spelling of 21368457 in words is "twenty-one million, three hundred sixty-eight thousand, four hundred fifty-seven".