157697991 has 24 divisors (see below), whose sum is σ = 250833024. Its totient is φ = 94674960.

The previous prime is 157697987. The next prime is 157698011. The reversal of 157697991 is 199796751.

It is a happy number.

It is not a de Polignac number, because 157697991 - 2² = 157697987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (157697951) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3150 + ... + 18036.

It is an arithmetic number, because the mean of its divisors is an integer number (10451376).

Almost surely, 2^157697991 is an apocalyptic number.

157697991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

157697991 is a deficient number, since it is larger than the sum of its proper divisors (93135033).

157697991 is a wasteful number, since it uses less digits than its factorization.

157697991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15011 (or 15008 counting only the distinct ones).

The product of its digits is 1071630, while the sum is 54.

The square root of 157697991 is about 12557.7860708009. The cubic root of 157697991 is about 540.2673470419.

The spelling of 157697991 in words is "one hundred fifty-seven million, six hundred ninety-seven thousand, nine hundred ninety-one".