125631209 has 4 divisors (see below), whose sum is σ = 137052240. Its totient is φ = 114210180.

The previous prime is 125631203. The next prime is 125631223. The reversal of 125631209 is 902136521.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 125631209 - 2¹² = 125627113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (125631203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5710499 + ... + 5710520.

It is an arithmetic number, because the mean of its divisors is an integer number (34263060).

Almost surely, 2^125631209 is an apocalyptic number.

It is an amenable number.

125631209 is a deficient number, since it is larger than the sum of its proper divisors (11421031).

125631209 is a wasteful number, since it uses less digits than its factorization.

125631209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11421030.

The product of its (nonzero) digits is 3240, while the sum is 29.

The square root of 125631209 is about 11208.5328656341. The cubic root of 125631209 is about 500.8401993393.

The spelling of 125631209 in words is "one hundred twenty-five million, six hundred thirty-one thousand, two hundred nine".