21367857 has 16 divisors (see below), whose sum is σ = 32772992. Its totient is φ = 12130560.

The previous prime is 21367831. The next prime is 21367883. The reversal of 21367857 is 75876312.

It is an interprime number because it is at equal distance from previous prime (21367831) and next prime (21367883).

It is not a de Polignac number, because 21367857 - 2⁷ = 21367729 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21367807) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 57 + ... + 6537.

It is an arithmetic number, because the mean of its divisors is an integer number (2048312).

Almost surely, 2^21367857 is an apocalyptic number.

It is an amenable number.

21367857 is a deficient number, since it is larger than the sum of its proper divisors (11405135).

21367857 is a wasteful number, since it uses less digits than its factorization.

21367857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6648.

The product of its digits is 70560, while the sum is 39.

The square root of 21367857 is about 4622.5379392710. The cubic root of 21367857 is about 277.4940376935.

The spelling of 21367857 in words is "twenty-one million, three hundred sixty-seven thousand, eight hundred fifty-seven".