21874257 has 12 divisors (see below), whose sum is σ = 33454980. Its totient is φ = 13724928.

The previous prime is 21874241. The next prime is 21874261. The reversal of 21874257 is 75247812.

It can be written as a sum of positive squares in 2 ways, for example, as 7403841 + 14470416 = 2721^2 + 3804^2 .

It is not a de Polignac number, because 21874257 - 2⁴ = 21874241 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21874267) 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, 71332 + ... + 71637.

It is an arithmetic number, because the mean of its divisors is an integer number (2787915).

Almost surely, 2^21874257 is an apocalyptic number.

It is an amenable number.

21874257 is a deficient number, since it is larger than the sum of its proper divisors (11580723).

21874257 is a wasteful number, since it uses less digits than its factorization.

21874257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142992 (or 142989 counting only the distinct ones).

The product of its digits is 31360, while the sum is 36.

The square root of 21874257 is about 4676.9923027518. The cubic root of 21874257 is about 279.6690690621.

The spelling of 21874257 in words is "twenty-one million, eight hundred seventy-four thousand, two hundred fifty-seven".