125645991 has 4 divisors (see below), whose sum is σ = 167527992. Its totient is φ = 83763992.

The previous prime is 125645983. The next prime is 125646023. The reversal of 125645991 is 199546521.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 125645991 - 2³ = 125645983 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125644991) 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 in 3 ways as a sum of consecutive naturals, for example, 20940996 + ... + 20941001.

It is an arithmetic number, because the mean of its divisors is an integer number (41881998).

Almost surely, 2^125645991 is an apocalyptic number.

125645991 is a deficient number, since it is larger than the sum of its proper divisors (41882001).

125645991 is an equidigital number, since it uses as much as digits as its factorization.

125645991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41882000.

The product of its digits is 97200, while the sum is 42.

The square root of 125645991 is about 11209.1922545739. The cubic root of 125645991 is about 500.8598418298.

The spelling of 125645991 in words is "one hundred twenty-five million, six hundred forty-five thousand, nine hundred ninety-one".