172085021 has 2 divisors, whose sum is σ = 172085022. Its totient is φ = 172085020.

The previous prime is 172085009. The next prime is 172085041. The reversal of 172085021 is 120580271.

172085021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 172003225 + 81796 = 13115^2 + 286^2 .

It is a cyclic number.

It is not a de Polignac number, because 172085021 - 2¹⁸ = 171822877 is a prime.

It is a super-2 number, since 2×172085021² = 59226508905140882, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (172085041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86042510 + 86042511.

It is an arithmetic number, because the mean of its divisors is an integer number (86042511).

Almost surely, 2^172085021 is an apocalyptic number.

It is an amenable number.

172085021 is a deficient number, since it is larger than the sum of its proper divisors (1).

172085021 is an equidigital number, since it uses as much as digits as its factorization.

172085021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1120, while the sum is 26.

The square root of 172085021 is about 13118.1180433780. The cubic root of 172085021 is about 556.2213947163.

The spelling of 172085021 in words is "one hundred seventy-two million, eighty-five thousand, twenty-one".