21256438 has 16 divisors (see below), whose sum is σ = 36510624. Its totient is φ = 9092160.

The previous prime is 21256399. The next prime is 21256447. The reversal of 21256438 is 83465212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8106 + ... + 10402.

It is an arithmetic number, because the mean of its divisors is an integer number (2281914).

Almost surely, 2^21256438 is an apocalyptic number.

21256438 is a deficient number, since it is larger than the sum of its proper divisors (15254186).

21256438 is a wasteful number, since it uses less digits than its factorization.

21256438 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2967.

The product of its digits is 11520, while the sum is 31.

The square root of 21256438 is about 4610.4704749082. The cubic root of 21256438 is about 277.0108820289.

The spelling of 21256438 in words is "twenty-one million, two hundred fifty-six thousand, four hundred thirty-eight".