21808377 has 12 divisors (see below), whose sum is σ = 32587620. Its totient is φ = 14037408.

The previous prime is 21808361. The next prime is 21808411. The reversal of 21808377 is 77380812.

It can be written as a sum of positive squares in 2 ways, for example, as 18481401 + 3326976 = 4299^2 + 1824^2 .

It is not a de Polignac number, because 21808377 - 2⁴ = 21808361 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21808307) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41518 + ... + 42039.

It is an arithmetic number, because the mean of its divisors is an integer number (2715635).

Almost surely, 2^21808377 is an apocalyptic number.

It is an amenable number.

21808377 is a deficient number, since it is larger than the sum of its proper divisors (10779243).

21808377 is a wasteful number, since it uses less digits than its factorization.

21808377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83592 (or 83589 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 36.

The square root of 21808377 is about 4669.9440039469. The cubic root of 21808377 is about 279.3880214041.

The spelling of 21808377 in words is "twenty-one million, eight hundred eight thousand, three hundred seventy-seven".