155681 has 4 divisors (see below), whose sum is σ = 156864. Its totient is φ = 154500.

The previous prime is 155671. The next prime is 155689. The reversal of 155681 is 186551.

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.

It is a cyclic number.

It is not a de Polignac number, because 155681 - 2¹⁴ = 139297 is a prime.

It is a super-2 number, since 2×155681² = 48473147522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 155681.

It is not an unprimeable number, because it can be changed into a prime (155689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 365 + ... + 666.

It is an arithmetic number, because the mean of its divisors is an integer number (39216).

2¹⁵⁵⁶⁸¹ is an apocalyptic number.

It is an amenable number.

155681 is a deficient number, since it is larger than the sum of its proper divisors (1183).

155681 is a wasteful number, since it uses less digits than its factorization.

155681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1182.

The product of its digits is 1200, while the sum is 26.

The square root of 155681 is about 394.5643166836. The cubic root of 155681 is about 53.7954078160.

The spelling of 155681 in words is "one hundred fifty-five thousand, six hundred eighty-one".