21947772 has 48 divisors (see below), whose sum is σ = 63850752. Its totient is φ = 5700480.

The previous prime is 21947747. The next prime is 21947791. The reversal of 21947772 is 27774912.

It is a self number, because there is not a number n which added to its sum of digits gives 21947772.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10953 + ... + 12800.

It is an arithmetic number, because the mean of its divisors is an integer number (1330224).

Almost surely, 2^21947772 is an apocalyptic number.

21947772 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21947772 is an abundant number, since it is smaller than the sum of its proper divisors (41902980).

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

21947772 is a wasteful number, since it uses less digits than its factorization.

21947772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23778 (or 23776 counting only the distinct ones).

The product of its digits is 49392, while the sum is 39.

The square root of 21947772 is about 4684.8449280633. The cubic root of 21947772 is about 279.9820226553.

The spelling of 21947772 in words is "twenty-one million, nine hundred forty-seven thousand, seven hundred seventy-two".