21983905 has 4 divisors (see below), whose sum is σ = 26380692. Its totient is φ = 17587120.

The previous prime is 21983887. The next prime is 21983911. The reversal of 21983905 is 50938912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7551504 + 14432401 = 2748^2 + 3799^2 .

It is not a de Polignac number, because 21983905 - 2²³ = 13595297 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 2198386 + ... + 2198395.

It is an arithmetic number, because the mean of its divisors is an integer number (6595173).

Almost surely, 2^21983905 is an apocalyptic number.

It is an amenable number.

21983905 is a deficient number, since it is larger than the sum of its proper divisors (4396787).

21983905 is an equidigital number, since it uses as much as digits as its factorization.

21983905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4396786.

The product of its (nonzero) digits is 19440, while the sum is 37.

The square root of 21983905 is about 4688.6997131401. The cubic root of 21983905 is about 280.1355848451.

The spelling of 21983905 in words is "twenty-one million, nine hundred eighty-three thousand, nine hundred five".