21905793 has 36 divisors (see below), whose sum is σ = 39649428. Its totient is φ = 11551680.

The previous prime is 21905783. The next prime is 21905797. The reversal of 21905793 is 39750912.

It can be written as a sum of positive squares in 2 ways, for example, as 11716929 + 10188864 = 3423^2 + 3192^2 .

It is not a de Polignac number, because 21905793 - 2⁵ = 21905761 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21905797) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3823 + ... + 7643.

It is an arithmetic number, because the mean of its divisors is an integer number (1101373).

Almost surely, 2^21905793 is an apocalyptic number.

It is an amenable number.

21905793 is a deficient number, since it is larger than the sum of its proper divisors (17743635).

21905793 is a wasteful number, since it uses less digits than its factorization.

21905793 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3854 (or 3844 counting only the distinct ones).

The product of its (nonzero) digits is 17010, while the sum is 36.

The square root of 21905793 is about 4680.3624859620. The cubic root of 21905793 is about 279.8034036628.

The spelling of 21905793 in words is "twenty-one million, nine hundred five thousand, seven hundred ninety-three".