172721645 has 8 divisors (see below), whose sum is σ = 210359904. Its totient is φ = 136114704.

The previous prime is 172721639. The next prime is 172721693. The reversal of 172721645 is 546127271.

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 172721645 - 2⁸ = 172721389 is a prime.

It is a super-3 number, since 3×172721645³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 257459 + ... + 258128.

It is an arithmetic number, because the mean of its divisors is an integer number (26294988).

Almost surely, 2^172721645 is an apocalyptic number.

It is an amenable number.

172721645 is a deficient number, since it is larger than the sum of its proper divisors (37638259).

172721645 is an equidigital number, since it uses as much as digits as its factorization.

172721645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 515659.

The product of its digits is 23520, while the sum is 35.

The square root of 172721645 is about 13142.3607087920. The cubic root of 172721645 is about 556.9064594136.

The spelling of 172721645 in words is "one hundred seventy-two million, seven hundred twenty-one thousand, six hundred forty-five".