1991718 has 12 divisors (see below), whose sum is σ = 4315428. Its totient is φ = 663900.

The previous prime is 1991707. The next prime is 1991723. The reversal of 1991718 is 8171991.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 55308 + ... + 55343.

It is an arithmetic number, because the mean of its divisors is an integer number (359619).

2^1991718 is an apocalyptic number.

1991718 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1991718 is an abundant number, since it is smaller than the sum of its proper divisors (2323710).

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

1991718 is a wasteful number, since it uses less digits than its factorization.

1991718 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110659 (or 110656 counting only the distinct ones).

The product of its digits is 4536, while the sum is 36.

The square root of 1991718 is about 1411.2823955538. The cubic root of 1991718 is about 125.8179532782.

The spelling of 1991718 in words is "one million, nine hundred ninety-one thousand, seven hundred eighteen".