21455764 has 24 divisors (see below), whose sum is σ = 41428800. Its totient is φ = 9641280.

The previous prime is 21455743. The next prime is 21455767. The reversal of 21455764 is 46755412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21455767) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1177 + ... + 6655.

It is an arithmetic number, because the mean of its divisors is an integer number (1726200).

Almost surely, 2^21455764 is an apocalyptic number.

It is an amenable number.

21455764 is a deficient number, since it is larger than the sum of its proper divisors (19973036).

21455764 is a wasteful number, since it uses less digits than its factorization.

21455764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5583 (or 5581 counting only the distinct ones).

The product of its digits is 33600, while the sum is 34.

The square root of 21455764 is about 4632.0367010636. The cubic root of 21455764 is about 277.8740522937.

The spelling of 21455764 in words is "twenty-one million, four hundred fifty-five thousand, seven hundred sixty-four".