21131164 has 12 divisors (see below), whose sum is σ = 37486624. Its totient is φ = 10420704.

The previous prime is 21131161. The next prime is 21131179. The reversal of 21131164 is 46113112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35892 + ... + 36475.

Almost surely, 2^21131164 is an apocalyptic number.

It is an amenable number.

21131164 is a deficient number, since it is larger than the sum of its proper divisors (16355460).

21131164 is a wasteful number, since it uses less digits than its factorization.

21131164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72444 (or 72442 counting only the distinct ones).

The product of its digits is 144, while the sum is 19.

The square root of 21131164 is about 4596.8645836048. The cubic root of 21131164 is about 276.4656251446.

Adding to 21131164 its reverse (46113112), we get a palindrome (67244276).

It can be divided in two parts, 211 and 31164, that added together give a triangular number (31375 = T₂₅₀).

The spelling of 21131164 in words is "twenty-one million, one hundred thirty-one thousand, one hundred sixty-four".