21857672 has 8 divisors (see below), whose sum is σ = 40983150. Its totient is φ = 10928832.

The previous prime is 21857669. The next prime is 21857681. The reversal of 21857672 is 27675812.

It can be written as a sum of positive squares in only one way, i.e., 12773476 + 9084196 = 3574^2 + 3014^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1366097 + ... + 1366112.

Almost surely, 2^21857672 is an apocalyptic number.

It is an amenable number.

21857672 is a deficient number, since it is larger than the sum of its proper divisors (19125478).

21857672 is a wasteful number, since it uses less digits than its factorization.

21857672 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2732215 (or 2732211 counting only the distinct ones).

The product of its digits is 47040, while the sum is 38.

The square root of 21857672 is about 4675.2189253553. The cubic root of 21857672 is about 279.5983697578.

The spelling of 21857672 in words is "twenty-one million, eight hundred fifty-seven thousand, six hundred seventy-two".