21772566 has 12 divisors (see below), whose sum is σ = 47173932. Its totient is φ = 7257516.

The previous prime is 21772561. The next prime is 21772567. The reversal of 21772566 is 66527712.

21772566 is a `hidden beast` number, since 21 + 7 + 72 + 566 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21772566.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21772561) 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 5 ways as a sum of consecutive naturals, for example, 604776 + ... + 604811.

It is an arithmetic number, because the mean of its divisors is an integer number (3931161).

Almost surely, 2^21772566 is an apocalyptic number.

21772566 is an abundant number, since it is smaller than the sum of its proper divisors (25401366).

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

21772566 is a wasteful number, since it uses less digits than its factorization.

21772566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1209595 (or 1209592 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21772566 is about 4666.1082284919. The cubic root of 21772566 is about 279.2350122210.

The spelling of 21772566 in words is "twenty-one million, seven hundred seventy-two thousand, five hundred sixty-six".