87991365865 has 8 divisors (see below), whose sum is σ = 113711919048. Its totient is φ = 64978239360.

The previous prime is 87991365859. The next prime is 87991365871. The reversal of 87991365865 is 56856319978.

It is an interprime number because it is at equal distance from previous prime (87991365859) and next prime (87991365871).

It can be written as a sum of positive squares in 4 ways, for example, as 4578416896 + 83412948969 = 67664^2 + 288813^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 87991365865 - 2²¹ = 87989268713 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 87991365865.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 676856596 + ... + 676856725.

It is an arithmetic number, because the mean of its divisors is an integer number (14213989881).

Almost surely, 2^87991365865 is an apocalyptic number.

It is an amenable number.

87991365865 is a deficient number, since it is larger than the sum of its proper divisors (25720553183).

87991365865 is a wasteful number, since it uses less digits than its factorization.

87991365865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1353713339.

The product of its digits is 97977600, while the sum is 67.

The spelling of 87991365865 in words is "eighty-seven billion, nine hundred ninety-one million, three hundred sixty-five thousand, eight hundred sixty-five".