21958805 has 16 divisors (see below), whose sum is σ = 28940544. Its totient is φ = 15862080.

The previous prime is 21958799. The next prime is 21958817. The reversal of 21958805 is 50885912.

It is not a de Polignac number, because 21958805 - 2⁸ = 21958549 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7364 + ... + 9906.

It is an arithmetic number, because the mean of its divisors is an integer number (1808784).

Almost surely, 2^21958805 is an apocalyptic number.

It is an amenable number.

21958805 is a deficient number, since it is larger than the sum of its proper divisors (6981739).

21958805 is a wasteful number, since it uses less digits than its factorization.

21958805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2716.

The product of its (nonzero) digits is 28800, while the sum is 38.

The square root of 21958805 is about 4686.0223004164. The cubic root of 21958805 is about 280.0289298340.

The spelling of 21958805 in words is "twenty-one million, nine hundred fifty-eight thousand, eight hundred five".