21720976 has 10 divisors (see below), whose sum is σ = 42084422. Its totient is φ = 10860480.

The previous prime is 21720953. The next prime is 21720983. The reversal of 21720976 is 67902712.

It can be written as a sum of positive squares in only one way, i.e., 20466576 + 1254400 = 4524^2 + 1120^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 678765 + ... + 678796.

Almost surely, 2^21720976 is an apocalyptic number.

It is an amenable number.

21720976 is a deficient number, since it is larger than the sum of its proper divisors (20363446).

21720976 is a wasteful number, since it uses less digits than its factorization.

21720976 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1357569 (or 1357563 counting only the distinct ones).

The product of its (nonzero) digits is 10584, while the sum is 34.

The square root of 21720976 is about 4660.5767883385. The cubic root of 21720976 is about 279.0142890812.

The spelling of 21720976 in words is "twenty-one million, seven hundred twenty thousand, nine hundred seventy-six".