172071721 has 8 divisors (see below), whose sum is σ = 173337984. Its totient is φ = 170810640.

The previous prime is 172071701. The next prime is 172071727. The reversal of 172071721 is 127170271.

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

It is a cyclic number.

It is not a de Polignac number, because 172071721 - 2⁵ = 172071689 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 172071721.

It is not an unprimeable number, because it can be changed into a prime (172071727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 84906 + ... + 86908.

It is an arithmetic number, because the mean of its divisors is an integer number (21667248).

Almost surely, 2^172071721 is an apocalyptic number.

It is an amenable number.

172071721 is a deficient number, since it is larger than the sum of its proper divisors (1266263).

172071721 is a wasteful number, since it uses less digits than its factorization.

172071721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2591.

The product of its (nonzero) digits is 1372, while the sum is 28.

The square root of 172071721 is about 13117.6111011114. The cubic root of 172071721 is about 556.2070647162.

It can be divided in two parts, 1720 and 71721, that added together give a square (73441 = 271²).

The spelling of 172071721 in words is "one hundred seventy-two million, seventy-one thousand, seven hundred twenty-one".