21874857 has 4 divisors (see below), whose sum is σ = 29166480. Its totient is φ = 14583236.

The previous prime is 21874843. The next prime is 21874891. The reversal of 21874857 is 75847812.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21874857 - 2¹⁰ = 21873833 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21874837) 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, 3645807 + ... + 3645812.

It is an arithmetic number, because the mean of its divisors is an integer number (7291620).

Almost surely, 2^21874857 is an apocalyptic number.

It is an amenable number.

21874857 is a deficient number, since it is larger than the sum of its proper divisors (7291623).

21874857 is an equidigital number, since it uses as much as digits as its factorization.

21874857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7291622.

The product of its digits is 125440, while the sum is 42.

The square root of 21874857 is about 4677.0564460994. The cubic root of 21874857 is about 279.6716260999.

The spelling of 21874857 in words is "twenty-one million, eight hundred seventy-four thousand, eight hundred fifty-seven".