85581581 has 4 divisors (see below), whose sum is σ = 88532700. Its totient is φ = 82630464.

The previous prime is 85581563. The next prime is 85581589. The reversal of 85581581 is 18518558.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 47955625 + 37625956 = 6925^2 + 6134^2 .

It is a cyclic number.

It is not a de Polignac number, because 85581581 - 2¹⁰ = 85580557 is a prime.

It is a super-2 number, since 2×85581581² = 14648414012919122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85581589) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1475516 + ... + 1475573.

It is an arithmetic number, because the mean of its divisors is an integer number (22133175).

Almost surely, 2^85581581 is an apocalyptic number.

It is an amenable number.

85581581 is a deficient number, since it is larger than the sum of its proper divisors (2951119).

85581581 is a wasteful number, since it uses less digits than its factorization.

85581581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2951118.

The product of its digits is 64000, while the sum is 41.

The square root of 85581581 is about 9251.0313479093. The cubic root of 85581581 is about 440.6834780526.

The spelling of 85581581 in words is "eighty-five million, five hundred eighty-one thousand, five hundred eighty-one".