1231865155 has 4 divisors (see below), whose sum is σ = 1478238192. Its totient is φ = 985492120.

The previous prime is 1231865137. The next prime is 1231865179. The reversal of 1231865155 is 5515681321.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1231865155 - 2¹⁵ = 1231832387 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 14.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123186511 + ... + 123186520.

It is an arithmetic number, because the mean of its divisors is an integer number (369559548).

Almost surely, 2^1231865155 is an apocalyptic number.

1231865155 is a deficient number, since it is larger than the sum of its proper divisors (246373037).

1231865155 is an equidigital number, since it uses as much as digits as its factorization.

1231865155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 246373036.

The product of its digits is 36000, while the sum is 37.

The square root of 1231865155 is about 35097.9366202630. The cubic root of 1231865155 is about 1071.9825690875.

The spelling of 1231865155 in words is "one billion, two hundred thirty-one million, eight hundred sixty-five thousand, one hundred fifty-five".