21186164 has 18 divisors (see below), whose sum is σ = 37607094. Its totient is φ = 10442400.

The previous prime is 21186149. The next prime is 21186169. The reversal of 21186164 is 46168112.

It can be written as a sum of positive squares in 3 ways, for example, as 18490000 + 2696164 = 4300^2 + 1642^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21186169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 92402 + ... + 92630.

It is an arithmetic number, because the mean of its divisors is an integer number (2089283).

Almost surely, 2^21186164 is an apocalyptic number.

It is an amenable number.

21186164 is a deficient number, since it is larger than the sum of its proper divisors (16420930).

21186164 is a wasteful number, since it uses less digits than its factorization.

21186164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 563 (or 332 counting only the distinct ones).

The product of its digits is 2304, while the sum is 29.

The square root of 21186164 is about 4602.8430344734. The cubic root of 21186164 is about 276.7052780743.

The spelling of 21186164 in words is "twenty-one million, one hundred eighty-six thousand, one hundred sixty-four".