21972799 has 4 divisors (see below), whose sum is σ = 22015336. Its totient is φ = 21930264.

The previous prime is 21972763. The next prime is 21972803. The reversal of 21972799 is 99727912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21972799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973799) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20484 + ... + 21529.

It is an arithmetic number, because the mean of its divisors is an integer number (5503834).

Almost surely, 2^21972799 is an apocalyptic number.

21972799 is a deficient number, since it is larger than the sum of its proper divisors (42537).

21972799 is an equidigital number, since it uses as much as digits as its factorization.

21972799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42536.

The product of its digits is 142884, while the sum is 46.

The square root of 21972799 is about 4687.5152266419. The cubic root of 21972799 is about 280.0884032083.

The spelling of 21972799 in words is "twenty-one million, nine hundred seventy-two thousand, seven hundred ninety-nine".