21755764 has 12 divisors (see below), whose sum is σ = 38958304. Its totient is φ = 10624824.

The previous prime is 21755761. The next prime is 21755803. The reversal of 21755764 is 46755712.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21755761) 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, 63072 + ... + 63415.

Almost surely, 2^21755764 is an apocalyptic number.

It is an amenable number.

21755764 is a deficient number, since it is larger than the sum of its proper divisors (17202540).

21755764 is a wasteful number, since it uses less digits than its factorization.

21755764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126534 (or 126532 counting only the distinct ones).

The product of its digits is 58800, while the sum is 37.

The square root of 21755764 is about 4664.3074512729. The cubic root of 21755764 is about 279.1631647094.

Subtracting from 21755764 its product of digits (58800), we obtain a square (21696964 = 4658²).

The spelling of 21755764 in words is "twenty-one million, seven hundred fifty-five thousand, seven hundred sixty-four".