681157 has 4 divisors (see below), whose sum is σ = 682816. Its totient is φ = 679500.

The previous prime is 681151. The next prime is 681167. The reversal of 681157 is 751186.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 751186 = 2 ⋅375593.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-681157 is a prime.

It is an Ulam number.

It is a Duffinian number.

681157 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (681151) 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, 298 + ... + 1204.

It is an arithmetic number, because the mean of its divisors is an integer number (170704).

2⁶⁸¹¹⁵⁷ is an apocalyptic number.

681157 is the 477-th hex number.

It is an amenable number.

681157 is a deficient number, since it is larger than the sum of its proper divisors (1659).

681157 is an equidigital number, since it uses as much as digits as its factorization.

681157 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1658.

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

The square root of 681157 is about 825.3223612626. The cubic root of 681157 is about 87.9864390260.

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

The spelling of 681157 in words is "six hundred eighty-one thousand, one hundred fifty-seven".