21305164 has 6 divisors (see below), whose sum is σ = 37284044. Its totient is φ = 10652580.

The previous prime is 21305159. The next prime is 21305173. The reversal of 21305164 is 46150312.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2663142 + ... + 2663149.

Almost surely, 2^21305164 is an apocalyptic number.

It is an amenable number.

21305164 is a deficient number, since it is larger than the sum of its proper divisors (15978880).

21305164 is a wasteful number, since it uses less digits than its factorization.

21305164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5326295 (or 5326293 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 21305164 is about 4615.7517264255. The cubic root of 21305164 is about 277.2223839409. Note that the first 3 decimals are identical.

Adding to 21305164 its reverse (46150312), we get a palindrome (67455476).

The spelling of 21305164 in words is "twenty-one million, three hundred five thousand, one hundred sixty-four".