172470821 has 2 divisors, whose sum is σ = 172470822. Its totient is φ = 172470820.

The previous prime is 172470803. The next prime is 172470827. The reversal of 172470821 is 128074271.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 104325796 + 68145025 = 10214^2 + 8255^2 .

It is a cyclic number.

It is not a de Polignac number, because 172470821 - 2¹⁰ = 172469797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172470827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86235410 + 86235411.

It is an arithmetic number, because the mean of its divisors is an integer number (86235411).

Almost surely, 2^172470821 is an apocalyptic number.

It is an amenable number.

172470821 is a deficient number, since it is larger than the sum of its proper divisors (1).

172470821 is an equidigital number, since it uses as much as digits as its factorization.

172470821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 6272, while the sum is 32.

The square root of 172470821 is about 13132.8146640391. The cubic root of 172470821 is about 556.6367515129.

The spelling of 172470821 in words is "one hundred seventy-two million, four hundred seventy thousand, eight hundred twenty-one".