21993799 has 4 divisors (see below), whose sum is σ = 22588264. Its totient is φ = 21399336.

The previous prime is 21993793. The next prime is 21993809. The reversal of 21993799 is 99739912.

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

It is a cyclic number.

It is not a de Polignac number, because 21993799 - 2⁹ = 21993287 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 (21993793) 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, 297177 + ... + 297250.

It is an arithmetic number, because the mean of its divisors is an integer number (5647066).

Almost surely, 2^21993799 is an apocalyptic number.

21993799 is a deficient number, since it is larger than the sum of its proper divisors (594465).

21993799 is an equidigital number, since it uses as much as digits as its factorization.

21993799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594464.

The product of its digits is 275562, while the sum is 49.

The square root of 21993799 is about 4689.7546844158. The cubic root of 21993799 is about 280.1776041585.

The spelling of 21993799 in words is "twenty-one million, nine hundred ninety-three thousand, seven hundred ninety-nine".