87890809 has 4 divisors (see below), whose sum is σ = 87917940. Its totient is φ = 87863680.

The previous prime is 87890791. The next prime is 87890819. The reversal of 87890809 is 90809878.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 90809878 = 2 ⋅45404939.

It can be written as a sum of positive squares in 2 ways, for example, as 23040000 + 64850809 = 4800^2 + 8053^2 .

It is a cyclic number.

It is not a de Polignac number, because 87890809 - 2⁷ = 87890681 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87890819) 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, 7924 + ... + 15445.

It is an arithmetic number, because the mean of its divisors is an integer number (21979485).

Almost surely, 2^87890809 is an apocalyptic number.

It is an amenable number.

87890809 is a deficient number, since it is larger than the sum of its proper divisors (27131).

87890809 is a wasteful number, since it uses less digits than its factorization.

87890809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27130.

The product of its (nonzero) digits is 290304, while the sum is 49.

The square root of 87890809 is about 9375.0098133282. The cubic root of 87890809 is about 444.6119733275.

The spelling of 87890809 in words is "eighty-seven million, eight hundred ninety thousand, eight hundred nine".