1991373144 has 24 divisors (see below), whose sum is σ = 4978979460. Its totient is φ = 663718176.

The previous prime is 1991373091. The next prime is 1991373151. The reversal of 1991373144 is 4413731991.

It is a tau number, because it is divible by the number of its divisors (24).

It is a junction number, because it is equal to n+sod(n) for n = 1991373096 and 1991373105.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 214062 + ... + 223170.

Almost surely, 2^1991373144 is an apocalyptic number.

It is an amenable number.

1991373144 is an abundant number, since it is smaller than the sum of its proper divisors (2987606316).

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

1991373144 is an frugal number, since it uses more digits than its factorization.

1991373144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18227 (or 9114 counting only the distinct ones).

The product of its digits is 81648, while the sum is 42.

The square root of 1991373144 is about 44624.8041340239. The cubic root of 1991373144 is about 1258.1069127611.

The spelling of 1991373144 in words is "one billion, nine hundred ninety-one million, three hundred seventy-three thousand, one hundred forty-four".