157691 has 4 divisors (see below), whose sum is σ = 159984. Its totient is φ = 155400.

The previous prime is 157679. The next prime is 157721. The reversal of 157691 is 196751.

It is a happy number.

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 157691 - 2⁶ = 157627 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 157691.

It is not an unprimeable number, because it can be changed into a prime (157291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1040 + ... + 1181.

It is an arithmetic number, because the mean of its divisors is an integer number (39996).

2¹⁵⁷⁶⁹¹ is an apocalyptic number.

157691 is a deficient number, since it is larger than the sum of its proper divisors (2293).

157691 is an equidigital number, since it uses as much as digits as its factorization.

157691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2292.

The product of its digits is 1890, while the sum is 29.

The square root of 157691 is about 397.1032611299. The cubic root of 157691 is about 54.0259363290.

Subtracting 157691 from its reverse (196751), we obtain a triangular number (39060 = T₂₇₉).

It can be divided in two parts, 157 and 691, that added together give a palindrome (848).

The spelling of 157691 in words is "one hundred fifty-seven thousand, six hundred ninety-one".