1991530598656 has 81 divisors (see below), whose sum is σ = 4004748902511. Its totient is φ = 988438265856.

The previous prime is 1991530598653. The next prime is 1991530598669. The reversal of 1991530598656 is 6568950351991.

The square root of 1991530598656 is 1411216.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 37797581056 + 1953733017600 = 194416^2 + 1397760^2 .

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1991530598591 and 1991530598600.

It is not an unprimeable number, because it can be changed into a prime (1991530598653) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 4357834780 + ... + 4357835236.

Almost surely, 2^{1991530598656} is an apocalyptic number.

1991530598656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

1991530598656 is the 1411216-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991530598656

1991530598656 is an abundant number, since it is smaller than the sum of its proper divisors (2013218303855).

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

1991530598656 is an frugal number, since it uses more digits than its factorization.

1991530598656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1316 (or 652 counting only the distinct ones).

The product of its (nonzero) digits is 78732000, while the sum is 67.

The spelling of 1991530598656 in words is "one trillion, nine hundred ninety-one billion, five hundred thirty million, five hundred ninety-eight thousand, six hundred fifty-six".