155501989 has 2 divisors, whose sum is σ = 155501990. Its totient is φ = 155501988.

The previous prime is 155501977. The next prime is 155502007. The reversal of 155501989 is 989105551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 155500900 + 1089 = 12470^2 + 33^2 .

It is a cyclic number.

It is not a de Polignac number, because 155501989 - 2⁹ = 155501477 is a prime.

It is a super-2 number, since 2×155501989² = 48361737165912242, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155501939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77750994 + 77750995.

It is an arithmetic number, because the mean of its divisors is an integer number (77750995).

Almost surely, 2^155501989 is an apocalyptic number.

It is an amenable number.

155501989 is a deficient number, since it is larger than the sum of its proper divisors (1).

155501989 is an equidigital number, since it uses as much as digits as its factorization.

155501989 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 81000, while the sum is 43.

The square root of 155501989 is about 12470.0436647191. The cubic root of 155501989 is about 537.7478088623.

The spelling of 155501989 in words is "one hundred fifty-five million, five hundred one thousand, nine hundred eighty-nine".