21230664 has 64 divisors (see below), whose sum is σ = 65331840. Its totient is φ = 5598720.

The previous prime is 21230641. The next prime is 21230689. The reversal of 21230664 is 46603212.

It is a Harshad number since it is a multiple of its sum of digits (24).

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 15 ways as a sum of consecutive naturals, for example, 2677 + ... + 7044.

It is an arithmetic number, because the mean of its divisors is an integer number (1020810).

Almost surely, 2^21230664 is an apocalyptic number.

21230664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21230664 is an abundant number, since it is smaller than the sum of its proper divisors (44101176).

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

21230664 is a wasteful number, since it uses less digits than its factorization.

21230664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9750 (or 9746 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 24.

The square root of 21230664 is about 4607.6744676680. The cubic root of 21230664 is about 276.8988757103.

Adding to 21230664 its reverse (46603212), we get a palindrome (67833876).

It can be divided in two parts, 212 and 30664, that added together give a triangular number (30876 = T₂₄₈).

The spelling of 21230664 in words is "twenty-one million, two hundred thirty thousand, six hundred sixty-four".