181625581 has 2 divisors, whose sum is σ = 181625582. Its totient is φ = 181625580.

The previous prime is 181625537. The next prime is 181625623. The reversal of 181625581 is 185526181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 178649956 + 2975625 = 13366^2 + 1725^2 .

It is a cyclic number.

It is not a de Polignac number, because 181625581 - 2⁷ = 181625453 is a prime.

It is a super-2 number, since 2×181625581² = 65975703347175122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 181625581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181625681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90812790 + 90812791.

It is an arithmetic number, because the mean of its divisors is an integer number (90812791).

Almost surely, 2^181625581 is an apocalyptic number.

It is an amenable number.

181625581 is a deficient number, since it is larger than the sum of its proper divisors (1).

181625581 is an equidigital number, since it uses as much as digits as its factorization.

181625581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 19200, while the sum is 37.

The square root of 181625581 is about 13476.8535274373. The cubic root of 181625581 is about 566.3162264998.

The spelling of 181625581 in words is "one hundred eighty-one million, six hundred twenty-five thousand, five hundred eighty-one".