21910791 has 12 divisors (see below), whose sum is σ = 33984312. Its totient is φ = 12520368.

The previous prime is 21910753. The next prime is 21910799. The reversal of 21910791 is 19701912.

It is not a de Polignac number, because 21910791 - 2⁶ = 21910727 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21910799) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 74380 + ... + 74673.

It is an arithmetic number, because the mean of its divisors is an integer number (2832026).

Almost surely, 2^21910791 is an apocalyptic number.

21910791 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21910791 is a deficient number, since it is larger than the sum of its proper divisors (12073521).

21910791 is a wasteful number, since it uses less digits than its factorization.

21910791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 149070 (or 149063 counting only the distinct ones).

The product of its (nonzero) digits is 1134, while the sum is 30.

The square root of 21910791 is about 4680.8963885136. The cubic root of 21910791 is about 279.8246819166.

The spelling of 21910791 in words is "twenty-one million, nine hundred ten thousand, seven hundred ninety-one".