125599991 has 4 divisors (see below), whose sum is σ = 137018184. Its totient is φ = 114181800.

The previous prime is 125599973. The next prime is 125599993. The reversal of 125599991 is 199995521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199995521 = 11 ⋅18181411.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-125599991 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125599993) 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, 5709080 + ... + 5709101.

It is an arithmetic number, because the mean of its divisors is an integer number (34254546).

Almost surely, 2^125599991 is an apocalyptic number.

125599991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

125599991 is a deficient number, since it is larger than the sum of its proper divisors (11418193).

125599991 is a wasteful number, since it uses less digits than its factorization.

125599991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11418192.

The product of its digits is 328050, while the sum is 50.

The square root of 125599991 is about 11207.1401793678. The cubic root of 125599991 is about 500.7987114407.

The spelling of 125599991 in words is "one hundred twenty-five million, five hundred ninety-nine thousand, nine hundred ninety-one".