81587853 has 6 divisors (see below), whose sum is σ = 117849134. Its totient is φ = 54391896.

The previous prime is 81587851. The next prime is 81587873. The reversal of 81587853 is 35878518.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 81486729 + 101124 = 9027^2 + 318^2 .

It is not a de Polignac number, because 81587853 - 2¹ = 81587851 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81587799 and 81587808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81587851) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4532650 + ... + 4532667.

Almost surely, 2^81587853 is an apocalyptic number.

It is an amenable number.

81587853 is a deficient number, since it is larger than the sum of its proper divisors (36261281).

81587853 is a wasteful number, since it uses less digits than its factorization.

81587853 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9065323 (or 9065320 counting only the distinct ones).

The product of its digits is 268800, while the sum is 45.

The square root of 81587853 is about 9032.5994597347. The cubic root of 81587853 is about 433.7190537321.

The spelling of 81587853 in words is "eighty-one million, five hundred eighty-seven thousand, eight hundred fifty-three".