125561815 has 4 divisors (see below), whose sum is σ = 150674184. Its totient is φ = 100449448.

The previous prime is 125561791. The next prime is 125561833. The reversal of 125561815 is 518165521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 518165521 = 2789 ⋅185789.

It is a cyclic number.

It is not a de Polignac number, because 125561815 - 2¹⁹ = 125037527 is a prime.

It is a Duffinian number.

It is a congruent number.

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, 12556177 + ... + 12556186.

It is an arithmetic number, because the mean of its divisors is an integer number (37668546).

Almost surely, 2^125561815 is an apocalyptic number.

125561815 is a deficient number, since it is larger than the sum of its proper divisors (25112369).

125561815 is an equidigital number, since it uses as much as digits as its factorization.

125561815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25112368.

The product of its digits is 12000, while the sum is 34.

The square root of 125561815 is about 11205.4368500295. The cubic root of 125561815 is about 500.7479671989.

The spelling of 125561815 in words is "one hundred twenty-five million, five hundred sixty-one thousand, eight hundred fifteen".