172890091 has 4 divisors (see below), whose sum is σ = 188607384. Its totient is φ = 157172800.

The previous prime is 172890089. The next prime is 172890097. The reversal of 172890091 is 190098271.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 172890091 - 2¹ = 172890089 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 172890091.

It is not an unprimeable number, because it can be changed into a prime (172890097) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7858630 + ... + 7858651.

It is an arithmetic number, because the mean of its divisors is an integer number (47151846).

Almost surely, 2^172890091 is an apocalyptic number.

172890091 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

172890091 is a deficient number, since it is larger than the sum of its proper divisors (15717293).

172890091 is a wasteful number, since it uses less digits than its factorization.

172890091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15717292.

The product of its (nonzero) digits is 9072, while the sum is 37.

The square root of 172890091 is about 13148.7676608875. The cubic root of 172890091 is about 557.0874407579.

It can be divided in two parts, 1728 and 90091, that added together give a palindrome (91819).

The spelling of 172890091 in words is "one hundred seventy-two million, eight hundred ninety thousand, ninety-one".