158081981 has 2 divisors, whose sum is σ = 158081982. Its totient is φ = 158081980.

The previous prime is 158081977. The next prime is 158081999. The reversal of 158081981 is 189180851.

158081981 = 8890² + 8891².

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79049881 + 79032100 = 8891^2 + 8890^2 .

It is a cyclic number.

It is not a de Polignac number, because 158081981 - 2² = 158081977 is a prime.

It is a super-2 number, since 2×158081981² = 49979825433768722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen 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 (158081941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79040990 + 79040991.

It is an arithmetic number, because the mean of its divisors is an integer number (79040991).

Almost surely, 2^158081981 is an apocalyptic number.

158081981 is the 8891-st centered square number.

It is an amenable number.

158081981 is a deficient number, since it is larger than the sum of its proper divisors (1).

158081981 is an equidigital number, since it uses as much as digits as its factorization.

158081981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 41.

The square root of 158081981 is about 12573.0656961618. The cubic root of 158081981 is about 540.7055033359.

The spelling of 158081981 in words is "one hundred fifty-eight million, eighty-one thousand, nine hundred eighty-one".