158993981 has 2 divisors, whose sum is σ = 158993982. Its totient is φ = 158993980.

The previous prime is 158993969. The next prime is 158994001. The reversal of 158993981 is 189399851.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 155875225 + 3118756 = 12485^2 + 1766^2 .

It is a cyclic number.

It is not a de Polignac number, because 158993981 - 2²² = 154799677 is a prime.

It is a super-2 number, since 2×158993981² = 50558171988456722, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (158990981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79496990 + 79496991.

It is an arithmetic number, because the mean of its divisors is an integer number (79496991).

Almost surely, 2^158993981 is an apocalyptic number.

It is an amenable number.

158993981 is a deficient number, since it is larger than the sum of its proper divisors (1).

158993981 is an equidigital number, since it uses as much as digits as its factorization.

158993981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 699840, while the sum is 53.

The square root of 158993981 is about 12609.2815417850. The cubic root of 158993981 is about 541.7433153650.

The spelling of 158993981 in words is "one hundred fifty-eight million, nine hundred ninety-three thousand, nine hundred eighty-one".