159697991 has 4 divisors (see below), whose sum is σ = 159822984. Its totient is φ = 159573000.

The previous prime is 159697981. The next prime is 159698003. The reversal of 159697991 is 199796951.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 159697991 - 2²² = 155503687 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 (159697981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60560 + ... + 63141.

It is an arithmetic number, because the mean of its divisors is an integer number (39955746).

Almost surely, 2^159697991 is an apocalyptic number.

159697991 is a deficient number, since it is larger than the sum of its proper divisors (124993).

159697991 is a wasteful number, since it uses less digits than its factorization.

159697991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124992.

The product of its digits is 1377810, while the sum is 56.

The square root of 159697991 is about 12637.1670480373. The cubic root of 159697991 is about 542.5417337839.

The spelling of 159697991 in words is "one hundred fifty-nine million, six hundred ninety-seven thousand, nine hundred ninety-one".