172215581 has 2 divisors, whose sum is σ = 172215582. Its totient is φ = 172215580.

The previous prime is 172215551. The next prime is 172215611. The reversal of 172215581 is 185512271.

172215581 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (172215551) and next prime (172215611).

It can be written as a sum of positive squares in only one way, i.e., 138180025 + 34035556 = 11755^2 + 5834^2 .

It is a cyclic number.

It is not a de Polignac number, because 172215581 - 2⁶ = 172215517 is a prime.

It is a super-2 number, since 2×172215581² = 59316412678335122, 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 (172215521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 86107790 + 86107791.

It is an arithmetic number, because the mean of its divisors is an integer number (86107791).

Almost surely, 2^172215581 is an apocalyptic number.

It is an amenable number.

172215581 is a deficient number, since it is larger than the sum of its proper divisors (1).

172215581 is an equidigital number, since it uses as much as digits as its factorization.

172215581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5600, while the sum is 32.

The square root of 172215581 is about 13123.0934234273. The cubic root of 172215581 is about 556.3620265720.

The spelling of 172215581 in words is "one hundred seventy-two million, two hundred fifteen thousand, five hundred eighty-one".