157681 has 8 divisors (see below), whose sum is σ = 170720. Its totient is φ = 145152.

The previous prime is 157679. The next prime is 157721. The reversal of 157681 is 186751.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 157681 - 2¹ = 157679 is a prime.

It is a super-2 number, since 2×157681² = 49726595522, which contains 22 as substring.

It is a Duffinian number.

157681 is a lucky number.

It is a plaindrome in base 7.

It is not an unprimeable number, because it can be changed into a prime (157081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 721 + ... + 913.

It is an arithmetic number, because the mean of its divisors is an integer number (21340).

2¹⁵⁷⁶⁸¹ is an apocalyptic number.

It is an amenable number.

157681 is a deficient number, since it is larger than the sum of its proper divisors (13039).

157681 is a wasteful number, since it uses less digits than its factorization.

157681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 255.

The product of its digits is 1680, while the sum is 28.

The square root of 157681 is about 397.0906697468. The cubic root of 157681 is about 54.0247942837.

It can be divided in two parts, 157 and 681, that added together give a palindrome (838).

The spelling of 157681 in words is "one hundred fifty-seven thousand, six hundred eighty-one".