1991640536 has 16 divisors (see below), whose sum is σ = 3749954400. Its totient is φ = 991652704.

The previous prime is 1991640499. The next prime is 1991640583. The reversal of 1991640536 is 6350461991.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 518915 + ... + 522738.

It is an arithmetic number, because the mean of its divisors is an integer number (234372150).

Almost surely, 2^1991640536 is an apocalyptic number.

It is an amenable number.

1991640536 is a deficient number, since it is larger than the sum of its proper divisors (1758313864).

1991640536 is a wasteful number, since it uses less digits than its factorization.

1991640536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1041898 (or 1041894 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 44.

The square root of 1991640536 is about 44627.8000354039. The cubic root of 1991640536 is about 1258.1632210876.

The spelling of 1991640536 in words is "one billion, nine hundred ninety-one million, six hundred forty thousand, five hundred thirty-six".