21912797 has 6 divisors (see below), whose sum is σ = 22361022. Its totient is φ = 21465912.

The previous prime is 21912791. The next prime is 21912799. The reversal of 21912797 is 79721912.

It can be written as a sum of positive squares in only one way, i.e., 20259001 + 1653796 = 4501^2 + 1286^2 .

It is not a de Polignac number, because 21912797 - 2⁶ = 21912733 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21912797.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21912791) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 33758 + ... + 34400.

It is an arithmetic number, because the mean of its divisors is an integer number (3726837).

Almost surely, 2^21912797 is an apocalyptic number.

It is an amenable number.

21912797 is a deficient number, since it is larger than the sum of its proper divisors (448225).

21912797 is an frugal number, since it uses more digits than its factorization.

21912797 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1339 (or 696 counting only the distinct ones).

The product of its digits is 15876, while the sum is 38.

The square root of 21912797 is about 4681.1106588074. The cubic root of 21912797 is about 279.8332212581.

The spelling of 21912797 in words is "twenty-one million, nine hundred twelve thousand, seven hundred ninety-seven".