125813781 has 24 divisors (see below), whose sum is σ = 186621240. Its totient is φ = 81648000.

The previous prime is 125813777. The next prime is 125813791. The reversal of 125813781 is 187318521.

125813781 is a `hidden beast` number, since 1 + 2 + 581 + 3 + 78 + 1 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1134225 + 124679556 = 1065^2 + 11166^2 .

It is not a de Polignac number, because 125813781 - 2² = 125813777 is a prime.

It is a super-2 number, since 2×125813781² = 31658214979031922, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125813711) 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, 54315 + ... + 56583.

It is an arithmetic number, because the mean of its divisors is an integer number (7775885).

Almost surely, 2^125813781 is an apocalyptic number.

It is an amenable number.

125813781 is a deficient number, since it is larger than the sum of its proper divisors (60807459).

125813781 is a wasteful number, since it uses less digits than its factorization.

125813781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2437 (or 2434 counting only the distinct ones).

The product of its digits is 13440, while the sum is 36.

The square root of 125813781 is about 11216.6742397201. The cubic root of 125813781 is about 501.0826951834.

The spelling of 125813781 in words is "one hundred twenty-five million, eight hundred thirteen thousand, seven hundred eighty-one".