22731991 has 2 divisors, whose sum is σ = 22731992. Its totient is φ = 22731990.

The previous prime is 22731983. The next prime is 22732001. The reversal of 22731991 is 19913722.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 22731991 - 2³ = 22731983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (22731931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 11365995 + 11365996.

It is an arithmetic number, because the mean of its divisors is an integer number (11365996).

Almost surely, 2^22731991 is an apocalyptic number.

22731991 is a deficient number, since it is larger than the sum of its proper divisors (1).

22731991 is an equidigital number, since it uses as much as digits as its factorization.

22731991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 34.

The square root of 22731991 is about 4767.8077771655. The cubic root of 22731991 is about 283.2777679579.

The spelling of 22731991 in words is "twenty-two million, seven hundred thirty-one thousand, nine hundred ninety-one".