21772656 has 60 divisors (see below), whose sum is σ = 62248992. Its totient is φ = 7100928.

The previous prime is 21772607. The next prime is 21772691. The reversal of 21772656 is 65627712.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a self number, because there is not a number n which added to its sum of digits gives 21772656.

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 11 ways as a sum of consecutive naturals, for example, 5160 + ... + 8376.

Almost surely, 2^21772656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21772656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31124496).

21772656 is an abundant number, since it is smaller than the sum of its proper divisors (40476336).

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

21772656 is a wasteful number, since it uses less digits than its factorization.

21772656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3278 (or 3269 counting only the distinct ones).

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

The square root of 21772656 is about 4666.1178724931. The cubic root of 21772656 is about 279.2353969730.

The spelling of 21772656 in words is "twenty-one million, seven hundred seventy-two thousand, six hundred fifty-six".