21010256 has 10 divisors (see below), whose sum is σ = 40707402. Its totient is φ = 10505120.

The previous prime is 21010237. The next prime is 21010259. The reversal of 21010256 is 65201012.

It can be written as a sum of positive squares in only one way, i.e., 20976400 + 33856 = 4580^2 + 184^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010259) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 656555 + ... + 656586.

Almost surely, 2^21010256 is an apocalyptic number.

It is an amenable number.

21010256 is a deficient number, since it is larger than the sum of its proper divisors (19697146).

21010256 is a wasteful number, since it uses less digits than its factorization.

21010256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1313149 (or 1313143 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21010256 is about 4583.6945797031. The cubic root of 21010256 is about 275.9373238624.

Adding to 21010256 its reverse (65201012), we get a palindrome (86211268).

The spelling of 21010256 in words is "twenty-one million, ten thousand, two hundred fifty-six".