125636721 has 16 divisors (see below), whose sum is σ = 201523200. Its totient is φ = 68013648.

The previous prime is 125636713. The next prime is 125636743. The reversal of 125636721 is 127636521.

It is not a de Polignac number, because 125636721 - 2³ = 125636713 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (125636221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 157041 + ... + 157838.

It is an arithmetic number, because the mean of its divisors is an integer number (12595200).

Almost surely, 2^125636721 is an apocalyptic number.

It is an amenable number.

125636721 is a deficient number, since it is larger than the sum of its proper divisors (75886479).

125636721 is a wasteful number, since it uses less digits than its factorization.

125636721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 314908.

The product of its digits is 15120, while the sum is 33.

The square root of 125636721 is about 11208.7787470357. The cubic root of 125636721 is about 500.8475239280.

The spelling of 125636721 in words is "one hundred twenty-five million, six hundred thirty-six thousand, seven hundred twenty-one".