87810813 has 6 divisors (see below), whose sum is σ = 126837854. Its totient is φ = 58540536.

The previous prime is 87810809. The next prime is 87810839. The reversal of 87810813 is 31801878.

It can be written as a sum of positive squares in only one way, i.e., 85433049 + 2377764 = 9243^2 + 1542^2 .

It is not a de Polignac number, because 87810813 - 2² = 87810809 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87810413) 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, 4878370 + ... + 4878387.

Almost surely, 2^87810813 is an apocalyptic number.

It is an amenable number.

87810813 is a deficient number, since it is larger than the sum of its proper divisors (39027041).

87810813 is a wasteful number, since it uses less digits than its factorization.

87810813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9756763 (or 9756760 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 36.

The square root of 87810813 is about 9370.7423932152. The cubic root of 87810813 is about 444.4770408431.

The spelling of 87810813 in words is "eighty-seven million, eight hundred ten thousand, eight hundred thirteen".