1125661581 has 24 divisors (see below), whose sum is σ = 1776815040. Its totient is φ = 681048000.

The previous prime is 1125661577. The next prime is 1125661597. The reversal of 1125661581 is 1851665211.

1125661581 is a `hidden beast` number, since 1 + 1 + 2 + 566 + 15 + 81 = 666.

It is not a de Polignac number, because 1125661581 - 2² = 1125661577 is a prime.

It is a super-2 number, since 2×1125661581² = 2534227989878839122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1125665581) 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, 50040 + ... + 68958.

It is an arithmetic number, because the mean of its divisors is an integer number (74033960).

Almost surely, 2^1125661581 is an apocalyptic number.

1125661581 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1125661581 is a deficient number, since it is larger than the sum of its proper divisors (651153459).

1125661581 is a wasteful number, since it uses less digits than its factorization.

1125661581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19537 (or 19534 counting only the distinct ones).

The product of its digits is 14400, while the sum is 36.

The square root of 1125661581 is about 33550.8804802497. The cubic root of 1125661581 is about 1040.2457447506.

The spelling of 1125661581 in words is "one billion, one hundred twenty-five million, six hundred sixty-one thousand, five hundred eighty-one".