155831195521 has 24 divisors (see below), whose sum is σ = 170143663616. Its totient is φ = 142589341440.

The previous prime is 155831195483. The next prime is 155831195551. The reversal of 155831195521 is 125591138551.

It is a happy number.

It is not a de Polignac number, because 155831195521 - 2²³ = 155822806913 is a prime.

It is a super-2 number, since 2×155831195521² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155831195551) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 15724450 + ... + 15734356.

Almost surely, 2^155831195521 is an apocalyptic number.

It is an amenable number.

155831195521 is a deficient number, since it is larger than the sum of its proper divisors (14312468095).

155831195521 is a wasteful number, since it uses less digits than its factorization.

155831195521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11449 (or 11432 counting only the distinct ones).

The product of its digits is 270000, while the sum is 46.

The spelling of 155831195521 in words is "one hundred fifty-five billion, eight hundred thirty-one million, one hundred ninety-five thousand, five hundred twenty-one".