125515561 has 2 divisors, whose sum is σ = 125515562. Its totient is φ = 125515560.

The previous prime is 125515553. The next prime is 125515591. The reversal of 125515561 is 165515521.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 111408025 + 14107536 = 10555^2 + 3756^2 .

It is a cyclic number.

It is not a de Polignac number, because 125515561 - 2³ = 125515553 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (125515591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 62757780 + 62757781.

It is an arithmetic number, because the mean of its divisors is an integer number (62757781).

Almost surely, 2^125515561 is an apocalyptic number.

It is an amenable number.

125515561 is a deficient number, since it is larger than the sum of its proper divisors (1).

125515561 is an equidigital number, since it uses as much as digits as its factorization.

125515561 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7500, while the sum is 31.

The square root of 125515561 is about 11203.3727510960. The cubic root of 125515561 is about 500.6864717484.

The spelling of 125515561 in words is "one hundred twenty-five million, five hundred fifteen thousand, five hundred sixty-one".