21831291 has 6 divisors (see below), whose sum is σ = 31534100. Its totient is φ = 14554188.

The previous prime is 21831263. The next prime is 21831353. The reversal of 21831291 is 19213812.

It is not a de Polignac number, because 21831291 - 2⁵ = 21831259 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21831091) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1212841 + ... + 1212858.

Almost surely, 2^21831291 is an apocalyptic number.

21831291 is a deficient number, since it is larger than the sum of its proper divisors (9702809).

21831291 is a wasteful number, since it uses less digits than its factorization.

21831291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2425705 (or 2425702 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 21831291 is about 4672.3967083286. The cubic root of 21831291 is about 279.4858378881.

It can be divided in two parts, 21831 and 291, that added together give a palindrome (22122).

The spelling of 21831291 in words is "twenty-one million, eight hundred thirty-one thousand, two hundred ninety-one".