1991919519 has 20 divisors (see below), whose sum is σ = 3002895720. Its totient is φ = 1315757520.

The previous prime is 1991919499. The next prime is 1991919557. The reversal of 1991919519 is 9159191991.

It is not a de Polignac number, because 1991919519 - 2¹¹ = 1991917471 is a prime.

It is a super-2 number, since 2×1991919519² = 7935486740346382722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991919619) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 103977 + ... + 121634.

It is an arithmetic number, because the mean of its divisors is an integer number (150144786).

Almost surely, 2^1991919519 is an apocalyptic number.

1991919519 is a deficient number, since it is larger than the sum of its proper divisors (1010976201).

1991919519 is a wasteful number, since it uses less digits than its factorization.

1991919519 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225732 (or 225723 counting only the distinct ones).

The product of its digits is 295245, while the sum is 54.

The square root of 1991919519 is about 44630.9255897746. The cubic root of 1991919519 is about 1258.2219649147.

The spelling of 1991919519 in words is "one billion, nine hundred ninety-one million, nine hundred nineteen thousand, five hundred nineteen".