172942821 has 6 divisors (see below), whose sum is σ = 249806310. Its totient is φ = 115295208.

The previous prime is 172942817. The next prime is 172942841. The reversal of 172942821 is 128249271.

It can be written as a sum of positive squares in only one way, i.e., 114190596 + 58752225 = 10686^2 + 7665^2 .

It is not a de Polignac number, because 172942821 - 2² = 172942817 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (172942801) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 9607926 + ... + 9607943.

It is an arithmetic number, because the mean of its divisors is an integer number (41634385).

Almost surely, 2^172942821 is an apocalyptic number.

It is an amenable number.

172942821 is a deficient number, since it is larger than the sum of its proper divisors (76863489).

172942821 is a wasteful number, since it uses less digits than its factorization.

172942821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19215875 (or 19215872 counting only the distinct ones).

The product of its digits is 16128, while the sum is 36.

The square root of 172942821 is about 13150.7726388984. The cubic root of 172942821 is about 557.1440706370.

The spelling of 172942821 in words is "one hundred seventy-two million, nine hundred forty-two thousand, eight hundred twenty-one".