21251164 has 24 divisors (see below), whose sum is σ = 40900608. Its totient is φ = 9581040.

The previous prime is 21251141. The next prime is 21251179. The reversal of 21251164 is 46115212.

It is a super-2 number, since 2×21251164² = 903223942709792, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3687 + ... + 7489.

It is an arithmetic number, because the mean of its divisors is an integer number (1704192).

Almost surely, 2^21251164 is an apocalyptic number.

It is an amenable number.

21251164 is a deficient number, since it is larger than the sum of its proper divisors (19649444).

21251164 is a wasteful number, since it uses less digits than its factorization.

21251164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3945 (or 3943 counting only the distinct ones).

The product of its digits is 480, while the sum is 22.

The square root of 21251164 is about 4609.8984804440. The cubic root of 21251164 is about 276.9879701275.

Adding to 21251164 its reverse (46115212), we get a palindrome (67366376).

The spelling of 21251164 in words is "twenty-one million, two hundred fifty-one thousand, one hundred sixty-four".