21926257 has 4 divisors (see below), whose sum is σ = 22071616. Its totient is φ = 21780900.

The previous prime is 21926161. The next prime is 21926293. The reversal of 21926257 is 75262912.

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 21926257 - 2²³ = 13537649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21926357) 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, 72453 + ... + 72754.

It is an arithmetic number, because the mean of its divisors is an integer number (5517904).

Almost surely, 2^21926257 is an apocalyptic number.

It is an amenable number.

21926257 is a deficient number, since it is larger than the sum of its proper divisors (145359).

21926257 is a wasteful number, since it uses less digits than its factorization.

21926257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145358.

The product of its digits is 15120, while the sum is 34.

The square root of 21926257 is about 4682.5481310927. The cubic root of 21926257 is about 279.8905056571.

The spelling of 21926257 in words is "twenty-one million, nine hundred twenty-six thousand, two hundred fifty-seven".