21445764 has 24 divisors (see below), whose sum is σ = 50123808. Its totient is φ = 7136640.

The previous prime is 21445759. The next prime is 21445793. The reversal of 21445764 is 46754412.

It is a congruent number.

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, 8844 + ... + 11004.

It is an arithmetic number, because the mean of its divisors is an integer number (2088492).

Almost surely, 2^21445764 is an apocalyptic number.

It is an amenable number.

21445764 is an abundant number, since it is smaller than the sum of its proper divisors (28678044).

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

21445764 is a wasteful number, since it uses less digits than its factorization.

21445764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2995 (or 2993 counting only the distinct ones).

The product of its digits is 26880, while the sum is 33.

The square root of 21445764 is about 4630.9571364892. The cubic root of 21445764 is about 277.8308755148.

The spelling of 21445764 in words is "twenty-one million, four hundred forty-five thousand, seven hundred sixty-four".