172090781 has 4 divisors (see below), whose sum is σ = 172133472. Its totient is φ = 172048092.

The previous prime is 172090777. The next prime is 172090783. The reversal of 172090781 is 187090271.

172090781 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 187090271 = 719 ⋅260209.

It is a cyclic number.

It is not a de Polignac number, because 172090781 - 2² = 172090777 is a prime.

It is a super-2 number, since 2×172090781² = 59230473810379922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172090783) 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, 14585 + ... + 23598.

It is an arithmetic number, because the mean of its divisors is an integer number (43033368).

Almost surely, 2^172090781 is an apocalyptic number.

It is an amenable number.

172090781 is a deficient number, since it is larger than the sum of its proper divisors (42691).

172090781 is an equidigital number, since it uses as much as digits as its factorization.

172090781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42690.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 172090781 is about 13118.3375852278. The cubic root of 172090781 is about 556.2276005625.

The spelling of 172090781 in words is "one hundred seventy-two million, ninety thousand, seven hundred eighty-one".