85815181 has 2 divisors, whose sum is σ = 85815182. Its totient is φ = 85815180.

The previous prime is 85815179. The next prime is 85815187. The reversal of 85815181 is 18151858.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78605956 + 7209225 = 8866^2 + 2685^2 .

It is a cyclic number.

It is not a de Polignac number, because 85815181 - 2¹ = 85815179 is a prime.

It is a super-2 number, since 2×85815181² = 14728490580125522, which contains 22 as substring.

Together with 85815179, it forms a pair of twin primes.

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 85815181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (85815187) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 42907590 + 42907591.

It is an arithmetic number, because the mean of its divisors is an integer number (42907591).

Almost surely, 2^85815181 is an apocalyptic number.

It is an amenable number.

85815181 is a deficient number, since it is larger than the sum of its proper divisors (1).

85815181 is an equidigital number, since it uses as much as digits as its factorization.

85815181 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12800, while the sum is 37.

The square root of 85815181 is about 9263.6483633609. The cubic root of 85815181 is about 441.0840710207.

The spelling of 85815181 in words is "eighty-five million, eight hundred fifteen thousand, one hundred eighty-one".