21612164 has 12 divisors (see below), whose sum is σ = 43224384. Its totient is φ = 9262344.

The previous prime is 21612133. The next prime is 21612179. The reversal of 21612164 is 46121612.

21612164 is an admirable number.

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, 385904 + ... + 385959.

It is an arithmetic number, because the mean of its divisors is an integer number (3602032).

Almost surely, 2^21612164 is an apocalyptic number.

It is an amenable number.

21612164 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21612164 is a wasteful number, since it uses less digits than its factorization.

21612164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 771874 (or 771872 counting only the distinct ones).

The product of its digits is 576, while the sum is 23.

The square root of 21612164 is about 4648.8884693010. Note that the first 3 decimals coincide. The cubic root of 21612164 is about 278.5475982495.

Adding to 21612164 its reverse (46121612), we get a palindrome (67733776).

The spelling of 21612164 in words is "twenty-one million, six hundred twelve thousand, one hundred sixty-four".