1991598656 has 28 divisors (see below), whose sum is σ = 3967855920. Its totient is φ = 991824000.

The previous prime is 1991598647. The next prime is 1991598673. The reversal of 1991598656 is 6568951991.

It is a junction number, because it is equal to n+sod(n) for n = 1991598595 and 1991598604.

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, 45926 + ... + 78053.

It is an arithmetic number, because the mean of its divisors is an integer number (141709140).

Almost surely, 2^1991598656 is an apocalyptic number.

1991598656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1991598656 is a deficient number, since it is larger than the sum of its proper divisors (1976257264).

1991598656 is a wasteful number, since it uses less digits than its factorization.

1991598656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124242 (or 124232 counting only the distinct ones).

The product of its digits is 5248800, while the sum is 59.

The square root of 1991598656 is about 44627.3308186811. The cubic root of 1991598656 is about 1258.1544021862.

The spelling of 1991598656 in words is "one billion, nine hundred ninety-one million, five hundred ninety-eight thousand, six hundred fifty-six".