21992317 has 2 divisors, whose sum is σ = 21992318. Its totient is φ = 21992316.

The previous prime is 21992303. The next prime is 21992351. The reversal of 21992317 is 71329912.

It is a happy number.

It is an a-pointer prime, because the next prime (21992351) can be obtained adding 21992317 to its sum of digits (34).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17023876 + 4968441 = 4126^2 + 2229^2 .

It is a cyclic number.

It is not a de Polignac number, because 21992317 - 2⁷ = 21992189 is a prime.

It is equal to p_1388824 and since 21992317 and 1388824 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21992357) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10996158 + 10996159.

It is an arithmetic number, because the mean of its divisors is an integer number (10996159).

Almost surely, 2^21992317 is an apocalyptic number.

It is an amenable number.

21992317 is a deficient number, since it is larger than the sum of its proper divisors (1).

21992317 is an equidigital number, since it uses as much as digits as its factorization.

21992317 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 21992317 is about 4689.5966777539. The cubic root of 21992317 is about 280.1713109826.

The spelling of 21992317 in words is "twenty-one million, nine hundred ninety-two thousand, three hundred seventeen".