158011991 has 32 divisors (see below), whose sum is σ = 181149696. Its totient is φ = 137088000.

The previous prime is 158011969. The next prime is 158011993. The reversal of 158011991 is 199110851.

158011991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a de Polignac number, because none of the positive numbers 2^k-158011991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (158011993) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1534046 + ... + 1534148.

It is an arithmetic number, because the mean of its divisors is an integer number (5660928).

Almost surely, 2^158011991 is an apocalyptic number.

158011991 is a deficient number, since it is larger than the sum of its proper divisors (23137705).

158011991 is a wasteful number, since it uses less digits than its factorization.

158011991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263.

The product of its (nonzero) digits is 3240, while the sum is 35.

The square root of 158011991 is about 12570.2820572969. The cubic root of 158011991 is about 540.6256933445.

The spelling of 158011991 in words is "one hundred fifty-eight million, eleven thousand, nine hundred ninety-one".