158971991 has 2 divisors, whose sum is σ = 158971992. Its totient is φ = 158971990.

The previous prime is 158971987. The next prime is 158972003. The reversal of 158971991 is 199179851.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 158971991 - 2² = 158971987 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (158971961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79485995 + 79485996.

It is an arithmetic number, because the mean of its divisors is an integer number (79485996).

Almost surely, 2^158971991 is an apocalyptic number.

158971991 is a deficient number, since it is larger than the sum of its proper divisors (1).

158971991 is an equidigital number, since it uses as much as digits as its factorization.

158971991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204120, while the sum is 50.

The square root of 158971991 is about 12608.4095349096. The cubic root of 158971991 is about 541.7183385605.

The spelling of 158971991 in words is "one hundred fifty-eight million, nine hundred seventy-one thousand, nine hundred ninety-one".