21722768 has 10 divisors (see below), whose sum is σ = 42087894. Its totient is φ = 10861376.

The previous prime is 21722759. The next prime is 21722791. The reversal of 21722768 is 86722712.

It can be written as a sum of positive squares in only one way, i.e., 20539024 + 1183744 = 4532^2 + 1088^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 678821 + ... + 678852.

Almost surely, 2^21722768 is an apocalyptic number.

It is an amenable number.

21722768 is a deficient number, since it is larger than the sum of its proper divisors (20365126).

21722768 is a wasteful number, since it uses less digits than its factorization.

21722768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1357681 (or 1357675 counting only the distinct ones).

The product of its digits is 18816, while the sum is 35.

The square root of 21722768 is about 4660.7690352559. The cubic root of 21722768 is about 279.0219618465.

The spelling of 21722768 in words is "twenty-one million, seven hundred twenty-two thousand, seven hundred sixty-eight".