21444764 has 12 divisors (see below), whose sum is σ = 40940088. Its totient is φ = 9747600.

The previous prime is 21444751. The next prime is 21444767. The reversal of 21444764 is 46744412.

It is a self number, because there is not a number n which added to its sum of digits gives 21444764.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21444767) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 243647 + ... + 243734.

It is an arithmetic number, because the mean of its divisors is an integer number (3411674).

Almost surely, 2^21444764 is an apocalyptic number.

It is an amenable number.

21444764 is a deficient number, since it is larger than the sum of its proper divisors (19495324).

21444764 is a wasteful number, since it uses less digits than its factorization.

21444764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 487396 (or 487394 counting only the distinct ones).

The product of its digits is 21504, while the sum is 32.

The square root of 21444764 is about 4630.8491661897. The cubic root of 21444764 is about 277.8265570988.

The spelling of 21444764 in words is "twenty-one million, four hundred forty-four thousand, seven hundred sixty-four".