125686619521 has 4 divisors (see below), whose sum is σ = 125716259844. Its totient is φ = 125656979200.

The previous prime is 125686619489. The next prime is 125686619557. The reversal of 125686619521 is 125916686521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 125916686521 = 17 ⋅7406863913.

It can be written as a sum of positive squares in 2 ways, for example, as 109465031025 + 16221588496 = 330855^2 + 127364^2 .

It is a cyclic number.

It is not a de Polignac number, because 125686619521 - 2⁵ = 125686619489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125686619581) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14813800 + ... + 14822281.

It is an arithmetic number, because the mean of its divisors is an integer number (31429064961).

Almost surely, 2^125686619521 is an apocalyptic number.

It is an amenable number.

125686619521 is a deficient number, since it is larger than the sum of its proper divisors (29640323).

125686619521 is an equidigital number, since it uses as much as digits as its factorization.

125686619521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29640322.

The product of its digits is 1555200, while the sum is 52.

The spelling of 125686619521 in words is "one hundred twenty-five billion, six hundred eighty-six million, six hundred nineteen thousand, five hundred twenty-one".