172121100 has 36 divisors (see below), whose sum is σ = 498004584. Its totient is φ = 45898880.

The previous prime is 172121099. The next prime is 172121123. The reversal of 172121100 is 1121271.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a self number, because there is not a number n which added to its sum of digits gives 172121100.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 286569 + ... + 287168.

Almost surely, 2^172121100 is an apocalyptic number.

172121100 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

172121100 is an abundant number, since it is smaller than the sum of its proper divisors (325883484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

172121100 is a wasteful number, since it uses less digits than its factorization.

172121100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573754 (or 573747 counting only the distinct ones).

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 172121100 is about 13119.4931304529. The cubic root of 172121100 is about 556.2602640870.

Adding to 172121100 its reverse (1121271), we get a palindrome (173242371).

The spelling of 172121100 in words is "one hundred seventy-two million, one hundred twenty-one thousand, one hundred".