21720592 has 10 divisors (see below), whose sum is σ = 42083678. Its totient is φ = 10860288.

The previous prime is 21720583. The next prime is 21720599. The reversal of 21720592 is 29502712.

It can be written as a sum of positive squares in only one way, i.e., 12503296 + 9217296 = 3536^2 + 3036^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21720592.

It is not an unprimeable number, because it can be changed into a prime (21720599) by changing a digit.

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 as a sum of consecutive naturals, namely, 678753 + ... + 678784.

Almost surely, 2^21720592 is an apocalyptic number.

It is an amenable number.

21720592 is a deficient number, since it is larger than the sum of its proper divisors (20363086).

21720592 is a wasteful number, since it uses less digits than its factorization.

21720592 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1357545 (or 1357539 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21720592 is about 4660.5355915388. The cubic root of 21720592 is about 279.0126448623.

The spelling of 21720592 in words is "twenty-one million, seven hundred twenty thousand, five hundred ninety-two".