21256738 has 8 divisors (see below), whose sum is σ = 33271488. Its totient is φ = 10166244.

The previous prime is 21256733. The next prime is 21256751. The reversal of 21256738 is 83765212.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (21256733) 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, 231006 + ... + 231097.

It is an arithmetic number, because the mean of its divisors is an integer number (4158936).

Almost surely, 2^21256738 is an apocalyptic number.

21256738 is a deficient number, since it is larger than the sum of its proper divisors (12014750).

21256738 is a wasteful number, since it uses less digits than its factorization.

21256738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 462128.

The product of its digits is 20160, while the sum is 34.

The square root of 21256738 is about 4610.5030094340. The cubic root of 21256738 is about 277.0121852086.

The spelling of 21256738 in words is "twenty-one million, two hundred fifty-six thousand, seven hundred thirty-eight".