21990807 has 12 divisors (see below), whose sum is σ = 32239480. Its totient is φ = 14441328.

The previous prime is 21990799. The next prime is 21990821. The reversal of 21990807 is 70809912.

It is a happy number.

It is not a de Polignac number, because 21990807 - 2³ = 21990799 is a prime.

It is a super-2 number, since 2×21990807² = 967191185022498, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21990887) 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, 17632 + ... + 18837.

Almost surely, 2^21990807 is an apocalyptic number.

21990807 is a deficient number, since it is larger than the sum of its proper divisors (10248673).

21990807 is a wasteful number, since it uses less digits than its factorization.

21990807 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36542 (or 36539 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 21990807 is about 4689.4356803351. The cubic root of 21990807 is about 280.1648986165.

The spelling of 21990807 in words is "twenty-one million, nine hundred ninety thousand, eight hundred seven".