21992704 has 18 divisors (see below), whose sum is σ = 43900010. Its totient is φ = 10996224.

The previous prime is 21992693. The next prime is 21992723. The reversal of 21992704 is 40729912.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 16000000 + 5992704 = 4000^2 + 2448^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21992704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42699 + ... + 43210.

Almost surely, 2^21992704 is an apocalyptic number.

It is an amenable number.

21992704 is a deficient number, since it is larger than the sum of its proper divisors (21907306).

21992704 is an frugal number, since it uses more digits than its factorization.

21992704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85925 (or 85911 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21992704 is about 4689.6379391164. The cubic root of 21992704 is about 280.1729543696.

The spelling of 21992704 in words is "twenty-one million, nine hundred ninety-two thousand, seven hundred four".