21455664 has 40 divisors (see below), whose sum is σ = 55733040. Its totient is φ = 7112448.

The previous prime is 21455663. The next prime is 21455677. The reversal of 21455664 is 46655412.

It is not an unprimeable number, because it can be changed into a prime (21455663) by changing a digit.

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, 8322 + ... + 10590.

It is an arithmetic number, because the mean of its divisors is an integer number (1393326).

Almost surely, 2^21455664 is an apocalyptic number.

21455664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21455664 is an abundant number, since it is smaller than the sum of its proper divisors (34277376).

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

21455664 is a wasteful number, since it uses less digits than its factorization.

21455664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2477 (or 2471 counting only the distinct ones).

The product of its digits is 28800, while the sum is 33.

The square root of 21455664 is about 4632.0259066633. The cubic root of 21455664 is about 277.8736205923.

The spelling of 21455664 in words is "twenty-one million, four hundred fifty-five thousand, six hundred sixty-four".