172081821 has 16 divisors (see below), whose sum is σ = 231368960. Its totient is φ = 113762880.

The previous prime is 172081807. The next prime is 172081859. The reversal of 172081821 is 128180271.

It is a happy number.

It is not a de Polignac number, because 172081821 - 2¹¹ = 172079773 is a prime.

It is a super-2 number, since 2×172081821² = 59224306237352082, 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 (172081801) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 317811 + ... + 318351.

It is an arithmetic number, because the mean of its divisors is an integer number (14460560).

Almost surely, 2^172081821 is an apocalyptic number.

It is an amenable number.

172081821 is a deficient number, since it is larger than the sum of its proper divisors (59287139).

172081821 is a wasteful number, since it uses less digits than its factorization.

172081821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1236.

The product of its (nonzero) digits is 1792, while the sum is 30.

The square root of 172081821 is about 13117.9960740961. The cubic root of 172081821 is about 556.2179469642.

The spelling of 172081821 in words is "one hundred seventy-two million, eighty-one thousand, eight hundred twenty-one".