21966857 has 16 divisors (see below), whose sum is σ = 25038720. Its totient is φ = 19094400.

The previous prime is 21966827. The next prime is 21966871. The reversal of 21966857 is 75866912.

It is a cyclic number.

It is not a de Polignac number, because 21966857 - 2¹⁰ = 21965833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21966827) 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, 23444 + ... + 24362.

It is an arithmetic number, because the mean of its divisors is an integer number (1564920).

Almost surely, 2^21966857 is an apocalyptic number.

It is an amenable number.

21966857 is a deficient number, since it is larger than the sum of its proper divisors (3071863).

21966857 is a wasteful number, since it uses less digits than its factorization.

21966857 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024.

The product of its digits is 181440, while the sum is 44.

The square root of 21966857 is about 4686.8813725120. The cubic root of 21966857 is about 280.0631532719.

It can be divided in two parts, 219 and 66857, that added together give a palindrome (67076).

The spelling of 21966857 in words is "twenty-one million, nine hundred sixty-six thousand, eight hundred fifty-seven".