1891991912 has 16 divisors (see below), whose sum is σ = 3548024100. Its totient is φ = 945852160.

The previous prime is 1891991867. The next prime is 1891991917. The reversal of 1891991912 is 2191991981.

It can be written as a sum of positive squares in 2 ways, for example, as 1867449796 + 24542116 = 43214^2 + 4954^2 .

It is not an unprimeable number, because it can be changed into a prime (1891991917) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55712 + ... + 82992.

Almost surely, 2^1891991912 is an apocalyptic number.

It is an amenable number.

1891991912 is a deficient number, since it is larger than the sum of its proper divisors (1656032188).

1891991912 is a wasteful number, since it uses less digits than its factorization.

1891991912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35956 (or 35952 counting only the distinct ones).

The product of its digits is 104976, while the sum is 50.

The square root of 1891991912 is about 43497.0333701047. The cubic root of 1891991912 is about 1236.8197886392.

The spelling of 1891991912 in words is "one billion, eight hundred ninety-one million, nine hundred ninety-one thousand, nine hundred twelve".