155091561 has 24 divisors (see below), whose sum is σ = 225077664. Its totient is φ = 94917120.

The previous prime is 155091551. The next prime is 155091569. The reversal of 155091561 is 165190551.

It is not a de Polignac number, because 155091561 - 2¹⁵ = 155058793 is a prime.

It is not an unprimeable number, because it can be changed into a prime (155091569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 33366 + ... + 37728.

It is an arithmetic number, because the mean of its divisors is an integer number (9378236).

Almost surely, 2^155091561 is an apocalyptic number.

It is an amenable number.

155091561 is a deficient number, since it is larger than the sum of its proper divisors (69986103).

155091561 is a wasteful number, since it uses less digits than its factorization.

155091561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4441 (or 4424 counting only the distinct ones).

The product of its (nonzero) digits is 6750, while the sum is 33.

The square root of 155091561 is about 12453.5762333556. The cubic root of 155091561 is about 537.2742860470.

The spelling of 155091561 in words is "one hundred fifty-five million, ninety-one thousand, five hundred sixty-one".