125609991 has 64 divisors (see below), whose sum is σ = 203212800. Its totient is φ = 68253696.

The previous prime is 125609989. The next prime is 125609993. The reversal of 125609991 is 199906521.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (125609989) and next prime (125609993).

It is not a de Polignac number, because 125609991 - 2¹ = 125609989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (125609993) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 903600 + ... + 903738.

It is an arithmetic number, because the mean of its divisors is an integer number (3175200).

Almost surely, 2^125609991 is an apocalyptic number.

125609991 is a deficient number, since it is larger than the sum of its proper divisors (77602809).

125609991 is a wasteful number, since it uses less digits than its factorization.

125609991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248.

The product of its (nonzero) digits is 43740, while the sum is 42.

The square root of 125609991 is about 11207.5863146353. The cubic root of 125609991 is about 500.8120019252.

The spelling of 125609991 in words is "one hundred twenty-five million, six hundred nine thousand, nine hundred ninety-one".