7991990 has 16 divisors (see below), whose sum is σ = 14443920. Its totient is φ = 3183840.

The previous prime is 7991981. The next prime is 7991993. The reversal of 7991990 is 991997.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7991993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1205 + ... + 4175.

It is an arithmetic number, because the mean of its divisors is an integer number (902745).

Almost surely, 2^7991990 is an apocalyptic number.

7991990 is a deficient number, since it is larger than the sum of its proper divisors (6451930).

7991990 is a wasteful number, since it uses less digits than its factorization.

7991990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3247.

The product of its (nonzero) digits is 45927, while the sum is 44.

The square root of 7991990 is about 2827.0107888015. The cubic root of 7991990 is about 199.9332277098.

The spelling of 7991990 in words is "seven million, nine hundred ninety-one thousand, nine hundred ninety".