127725721 has 4 divisors (see below), whose sum is σ = 127826100. Its totient is φ = 127625344.

The previous prime is 127725713. The next prime is 127725751. The reversal of 127725721 is 127527721.

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

It can be written as a sum of positive squares in 2 ways, for example, as 105267600 + 22458121 = 10260^2 + 4739^2 .

It is a cyclic number.

It is not a de Polignac number, because 127725721 - 2³ = 127725713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (127725751) 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, 48256 + ... + 50833.

It is an arithmetic number, because the mean of its divisors is an integer number (31956525).

Almost surely, 2^127725721 is an apocalyptic number.

It is an amenable number.

127725721 is a deficient number, since it is larger than the sum of its proper divisors (100379).

127725721 is an equidigital number, since it uses as much as digits as its factorization.

127725721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100378.

The product of its digits is 13720, while the sum is 34.

The square root of 127725721 is about 11301.5804646961. The cubic root of 127725721 is about 503.6081939064.

The spelling of 127725721 in words is "one hundred twenty-seven million, seven hundred twenty-five thousand, seven hundred twenty-one".