21070256 has 20 divisors (see below), whose sum is σ = 41595552. Its totient is φ = 10335936.

The previous prime is 21070237. The next prime is 21070267. The reversal of 21070256 is 65207012.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11576 + ... + 13271.

Almost surely, 2^21070256 is an apocalyptic number.

It is an amenable number.

21070256 is a deficient number, since it is larger than the sum of its proper divisors (20525296).

21070256 is a wasteful number, since it uses less digits than its factorization.

21070256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24908 (or 24902 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21070256 is about 4590.2348523796. The cubic root of 21070256 is about 276.1997433880.

Adding to 21070256 its reverse (65207012), we get a palindrome (86277268).

The spelling of 21070256 in words is "twenty-one million, seventy thousand, two hundred fifty-six".