21512164 has 12 divisors (see below), whose sum is σ = 37683324. Its totient is φ = 10745504.

The previous prime is 21512147. The next prime is 21512213. The reversal of 21512164 is 46121512.

It can be written as a sum of positive squares in 2 ways, for example, as 19873764 + 1638400 = 4458^2 + 1280^2 .

It is an unprimeable number.

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, 3534 + ... + 7450.

It is an arithmetic number, because the mean of its divisors is an integer number (3140277).

Almost surely, 2^21512164 is an apocalyptic number.

It is an amenable number.

21512164 is a deficient number, since it is larger than the sum of its proper divisors (16171160).

21512164 is a wasteful number, since it uses less digits than its factorization.

21512164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5294 (or 5292 counting only the distinct ones).

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

The square root of 21512164 is about 4638.1207401274. The cubic root of 21512164 is about 278.1173184597.

Adding to 21512164 its reverse (46121512), we get a palindrome (67633676).

The spelling of 21512164 in words is "twenty-one million, five hundred twelve thousand, one hundred sixty-four".