155921 has 2 divisors, whose sum is σ = 155922. Its totient is φ = 155920.

The previous prime is 155893. The next prime is 156007. The reversal of 155921 is 129551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 130321 + 25600 = 361^2 + 160^2 .

It is a cyclic number.

It is not a de Polignac number, because 155921 - 2¹⁰ = 154897 is a prime.

It is a super-2 number, since 2×155921² = 48622716482, which contains 22 as substring.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 155921.

It is not a weakly prime, because it can be changed into another prime (155521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77960 + 77961.

It is an arithmetic number, because the mean of its divisors is an integer number (77961).

2¹⁵⁵⁹²¹ is an apocalyptic number.

It is an amenable number.

155921 is a deficient number, since it is larger than the sum of its proper divisors (1).

155921 is an equidigital number, since it uses as much as digits as its factorization.

155921 is an evil number, because the sum of its binary digits is even.

The product of its digits is 450, while the sum is 23.

The square root of 155921 is about 394.8683324857. The cubic root of 155921 is about 53.8230375396.

The spelling of 155921 in words is "one hundred fifty-five thousand, nine hundred twenty-one".