21968905 has 12 divisors (see below), whose sum is σ = 30667140. Its totient is φ = 15064224.

The previous prime is 21968899. The next prime is 21968911. The reversal of 21968905 is 50986912.

It is an interprime number because it is at equal distance from previous prime (21968899) and next prime (21968911).

It can be written as a sum of positive squares in 2 ways, for example, as 7038409 + 14930496 = 2653^2 + 3864^2 .

It is not a de Polignac number, because 21968905 - 2⁹ = 21968393 is a prime.

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 11 ways as a sum of consecutive naturals, for example, 44590 + ... + 45079.

It is an arithmetic number, because the mean of its divisors is an integer number (2555595).

Almost surely, 2^21968905 is an apocalyptic number.

It is an amenable number.

21968905 is a deficient number, since it is larger than the sum of its proper divisors (8698235).

21968905 is an equidigital number, since it uses as much as digits as its factorization.

21968905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89688 (or 89681 counting only the distinct ones).

The product of its (nonzero) digits is 38880, while the sum is 40.

The square root of 21968905 is about 4687.0998495872. The cubic root of 21968905 is about 280.0718565578.

The spelling of 21968905 in words is "twenty-one million, nine hundred sixty-eight thousand, nine hundred five".