7991001 has 32 divisors (see below), whose sum is σ = 12828800. Its totient is φ = 4898880.

The previous prime is 7990999. The next prime is 7991017. The reversal of 7991001 is 1001997.

It is not a de Polignac number, because 7991001 - 2¹ = 7990999 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (7991101) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 18771 + ... + 19191.

It is an arithmetic number, because the mean of its divisors is an integer number (400900).

Almost surely, 2^7991001 is an apocalyptic number.

It is an amenable number.

7991001 is a deficient number, since it is larger than the sum of its proper divisors (4837799).

7991001 is a wasteful number, since it uses less digits than its factorization.

7991001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 486 (or 480 counting only the distinct ones).

The product of its (nonzero) digits is 567, while the sum is 27.

The square root of 7991001 is about 2826.8358636468. The cubic root of 7991001 is about 199.9249801970.

Adding to 7991001 its reverse (1001997), we get a palindrome (8992998).

The spelling of 7991001 in words is "seven million, nine hundred ninety-one thousand, one".