21251012 has 12 divisors (see below), whose sum is σ = 37258620. Its totient is φ = 10605696.

The previous prime is 21250979. The next prime is 21251017. The reversal of 21251012 is 21015212.

It can be written as a sum of positive squares in 2 ways, for example, as 12630916 + 8620096 = 3554^2 + 2936^2 .

It is a super-2 number, since 2×21251012² = 903211022048288, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21251017) 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, 2393 + ... + 6944.

It is an arithmetic number, because the mean of its divisors is an integer number (3104885).

Almost surely, 2^21251012 is an apocalyptic number.

It is an amenable number.

21251012 is a deficient number, since it is larger than the sum of its proper divisors (16007608).

21251012 is a wasteful number, since it uses less digits than its factorization.

21251012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9910 (or 9908 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21251012 is about 4609.8819941513. The cubic root of 21251012 is about 276.9873097359.

Adding to 21251012 its reverse (21015212), we get a palindrome (42266224).

The spelling of 21251012 in words is "twenty-one million, two hundred fifty-one thousand, twelve".