21993807 has 12 divisors (see below), whose sum is σ = 32233880. Its totient is φ = 13329360.

The previous prime is 21993793. The next prime is 21993809. The reversal of 21993807 is 70839912.

It is not a de Polignac number, because 21993807 - 2¹⁶ = 21928271 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 (21993809) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29932 + ... + 30657.

Almost surely, 2^21993807 is an apocalyptic number.

21993807 is a deficient number, since it is larger than the sum of its proper divisors (10240073).

21993807 is a wasteful number, since it uses less digits than its factorization.

21993807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60614 (or 60603 counting only the distinct ones).

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 21993807 is about 4689.7555373388. The cubic root of 21993807 is about 280.1776381290.

It can be divided in two parts, 2199 and 3807, that added together give a palindrome (6006).

The spelling of 21993807 in words is "twenty-one million, nine hundred ninety-three thousand, eight hundred seven".