155917681 has 2 divisors, whose sum is σ = 155917682. Its totient is φ = 155917680.

The previous prime is 155917669. The next prime is 155917687. The reversal of 155917681 is 186719551.

155917681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 155750400 + 167281 = 12480^2 + 409^2 .

It is a cyclic number.

It is not a de Polignac number, because 155917681 - 2¹⁵ = 155884913 is a prime.

It is a super-2 number, since 2×155917681² = 48620646496835522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (155917687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77958840 + 77958841.

It is an arithmetic number, because the mean of its divisors is an integer number (77958841).

Almost surely, 2^155917681 is an apocalyptic number.

It is an amenable number.

155917681 is a deficient number, since it is larger than the sum of its proper divisors (1).

155917681 is an equidigital number, since it uses as much as digits as its factorization.

155917681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 43.

The square root of 155917681 is about 12486.7001645751. The cubic root of 155917681 is about 538.2265563694.

The spelling of 155917681 in words is "one hundred fifty-five million, nine hundred seventeen thousand, six hundred eighty-one".