21831617 has 2 divisors, whose sum is σ = 21831618. Its totient is φ = 21831616.

The previous prime is 21831613. The next prime is 21831631. The reversal of 21831617 is 71613812.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21381376 + 450241 = 4624^2 + 671^2 .

It is a cyclic number.

It is not a de Polignac number, because 21831617 - 2² = 21831613 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21831617.

It is not a weakly prime, because it can be changed into another prime (21831613) by changing a digit.

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 as a sum of consecutive naturals, namely, 10915808 + 10915809.

It is an arithmetic number, because the mean of its divisors is an integer number (10915809).

Almost surely, 2^21831617 is an apocalyptic number.

It is an amenable number.

21831617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21831617 is an equidigital number, since it uses as much as digits as its factorization.

21831617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 21831617 is about 4672.4315939348. The cubic root of 21831617 is about 279.4872290400.

The spelling of 21831617 in words is "twenty-one million, eight hundred thirty-one thousand, six hundred seventeen".