172991985 has 8 divisors (see below), whose sum is σ = 276787200. Its totient is φ = 92262384.

The previous prime is 172991981. The next prime is 172991999. The reversal of 172991985 is 589199271.

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

It is not a de Polignac number, because 172991985 - 2² = 172991981 is a prime.

It is not an unprimeable number, because it can be changed into a prime (172991981) 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, 5766385 + ... + 5766414.

It is an arithmetic number, because the mean of its divisors is an integer number (34598400).

Almost surely, 2^172991985 is an apocalyptic number.

172991985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

172991985 is a deficient number, since it is larger than the sum of its proper divisors (103795215).

172991985 is a wasteful number, since it uses less digits than its factorization.

172991985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11532807.

The product of its digits is 408240, while the sum is 51.

The square root of 172991985 is about 13152.6417498539. The cubic root of 172991985 is about 557.1968604083.

The spelling of 172991985 in words is "one hundred seventy-two million, nine hundred ninety-one thousand, nine hundred eighty-five".