17957981 has 2 divisors, whose sum is σ = 17957982. Its totient is φ = 17957980.

The previous prime is 17957969. The next prime is 17957993. The reversal of 17957981 is 18975971.

It is a balanced prime because it is at equal distance from previous prime (17957969) and next prime (17957993).

It can be written as a sum of positive squares in only one way, i.e., 16728100 + 1229881 = 4090^2 + 1109^2 .

It is a cyclic number.

It is not a de Polignac number, because 17957981 - 2²² = 13763677 is a prime.

It is a super-2 number, since 2×17957981² = 644978163192722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (17957941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8978990 + 8978991.

It is an arithmetic number, because the mean of its divisors is an integer number (8978991).

Almost surely, 2^17957981 is an apocalyptic number.

It is an amenable number.

17957981 is a deficient number, since it is larger than the sum of its proper divisors (1).

17957981 is an equidigital number, since it uses as much as digits as its factorization.

17957981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 158760, while the sum is 47.

The square root of 17957981 is about 4237.6858071358. The cubic root of 17957981 is about 261.8700528796.

The spelling of 17957981 in words is "seventeen million, nine hundred fifty-seven thousand, nine hundred eighty-one".