21421256 has 16 divisors (see below), whose sum is σ = 41550300. Its totient is φ = 10341184.

The previous prime is 21421249. The next prime is 21421259. The reversal of 21421256 is 65212412.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19272100 + 2149156 = 4390^2 + 1466^2 .

It is not an unprimeable number, because it can be changed into a prime (21421259) 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, 45935 + ... + 46398.

Almost surely, 2^21421256 is an apocalyptic number.

It is an amenable number.

21421256 is a deficient number, since it is larger than the sum of its proper divisors (20129044).

21421256 is a wasteful number, since it uses less digits than its factorization.

21421256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92368 (or 92364 counting only the distinct ones).

The product of its digits is 960, while the sum is 23.

The square root of 21421256 is about 4628.3102748195. The cubic root of 21421256 is about 277.7250010785.

Adding to 21421256 its reverse (65212412), we get a palindrome (86633668).

The spelling of 21421256 in words is "twenty-one million, four hundred twenty-one thousand, two hundred fifty-six".