21320164 has 24 divisors (see below), whose sum is σ = 38779776. Its totient is φ = 10248000.

The previous prime is 21320107. The next prime is 21320183. The reversal of 21320164 is 46102312.

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 in 7 ways as a sum of consecutive naturals, for example, 10729 + ... + 12559.

It is an arithmetic number, because the mean of its divisors is an integer number (1615824).

Almost surely, 2^21320164 is an apocalyptic number.

It is an amenable number.

21320164 is a deficient number, since it is larger than the sum of its proper divisors (17459612).

21320164 is a wasteful number, since it uses less digits than its factorization.

21320164 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1947 (or 1945 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21320164 is about 4617.3763112833. The cubic root of 21320164 is about 277.2874285821.

Adding to 21320164 its reverse (46102312), we get a palindrome (67422476).

The spelling of 21320164 in words is "twenty-one million, three hundred twenty thousand, one hundred sixty-four".