7991865 has 40 divisors (see below), whose sum is σ = 16378560. Its totient is φ = 3652128.

The previous prime is 7991857. The next prime is 7991869. The reversal of 7991865 is 5681997.

It is not a de Polignac number, because 7991865 - 2³ = 7991857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 7991865.

It is not an unprimeable number, because it can be changed into a prime (7991869) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 1426 + ... + 4244.

It is an arithmetic number, because the mean of its divisors is an integer number (409464).

Almost surely, 2^7991865 is an apocalyptic number.

It is an amenable number.

7991865 is an abundant number, since it is smaller than the sum of its proper divisors (8386695).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7991865 is a wasteful number, since it uses less digits than its factorization.

7991865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2843 (or 2834 counting only the distinct ones).

The product of its digits is 136080, while the sum is 45.

The square root of 7991865 is about 2826.9886805575. The cubic root of 7991865 is about 199.9321853418.

The spelling of 7991865 in words is "seven million, nine hundred ninety-one thousand, eight hundred sixty-five".