172879721 has 8 divisors (see below), whose sum is σ = 198999360. Its totient is φ = 147115728.

The previous prime is 172879699. The next prime is 172879807. The reversal of 172879721 is 127978271.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-172879721 is a prime.

It is not an unprimeable number, because it can be changed into a prime (172839721) 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 7 ways as a sum of consecutive naturals, for example, 87866 + ... + 89811.

It is an arithmetic number, because the mean of its divisors is an integer number (24874920).

Almost surely, 2^172879721 is an apocalyptic number.

It is an amenable number.

172879721 is a deficient number, since it is larger than the sum of its proper divisors (26119639).

172879721 is a wasteful number, since it uses less digits than its factorization.

172879721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177823.

The product of its digits is 98784, while the sum is 44.

The square root of 172879721 is about 13148.3733214417. The cubic root of 172879721 is about 557.0763024440.

The spelling of 172879721 in words is "one hundred seventy-two million, eight hundred seventy-nine thousand, seven hundred twenty-one".