1991518776 has 48 divisors (see below), whose sum is σ = 5808599160. Its totient is φ = 612774720.

The previous prime is 1991518759. The next prime is 1991518783. The reversal of 1991518776 is 6778151991.

It is a super-2 number, since 2×1991518776² = 7932294070321076352, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1062910 + ... + 1064781.

Almost surely, 2^1991518776 is an apocalyptic number.

It is an amenable number.

1991518776 is an abundant number, since it is smaller than the sum of its proper divisors (3817080384).

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

1991518776 is a wasteful number, since it uses less digits than its factorization.

1991518776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2127716 (or 2127709 counting only the distinct ones).

The product of its digits is 952560, while the sum is 54.

The square root of 1991518776 is about 44626.4358424466. The cubic root of 1991518776 is about 1258.1375810733.

The spelling of 1991518776 in words is "one billion, nine hundred ninety-one million, five hundred eighteen thousand, seven hundred seventy-six".