172881221 has 4 divisors (see below), whose sum is σ = 173332992. Its totient is φ = 172429452.

The previous prime is 172881139. The next prime is 172881253. The reversal of 172881221 is 122188271.

It is a happy number.

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.

It is a cyclic number.

It is not a de Polignac number, because 172881221 - 2¹⁸ = 172619077 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172881421) 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, 225311 + ... + 226076.

It is an arithmetic number, because the mean of its divisors is an integer number (43333248).

Almost surely, 2^172881221 is an apocalyptic number.

It is an amenable number.

172881221 is a deficient number, since it is larger than the sum of its proper divisors (451771).

172881221 is an equidigital number, since it uses as much as digits as its factorization.

172881221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 451770.

The product of its digits is 3584, while the sum is 32.

The square root of 172881221 is about 13148.4303625946. The cubic root of 172881221 is about 557.0779136067.

The spelling of 172881221 in words is "one hundred seventy-two million, eight hundred eighty-one thousand, two hundred twenty-one".