1991766026250 has 1080 divisors, whose sum is σ = 7428826192788. Its totient is φ = 381870720000.

The previous prime is 1991766026119. The next prime is 1991766026297. The reversal of 1991766026250 is 526206671991.

1991766026250 is a `hidden beast` number, since 1 + 9 + 9 + 1 + 7 + 6 + 6 + 0 + 2 + 625 + 0 = 666.

It can be written as a sum of positive squares in 10 ways, for example, as 447838008849 + 1543928017401 = 669207^2 + 1242549^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 539 ways as a sum of consecutive naturals, for example, 867115102 + ... + 867117398.

Almost surely, 2^{1991766026250} is an apocalyptic number.

1991766026250 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1991766026250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3714413096394).

1991766026250 is an abundant number, since it is smaller than the sum of its proper divisors (5437060166538).

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

1991766026250 is a wasteful number, since it uses less digits than its factorization.

1991766026250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2374 (or 2338 counting only the distinct ones).

The product of its (nonzero) digits is 2449440, while the sum is 54.

The spelling of 1991766026250 in words is "one trillion, nine hundred ninety-one billion, seven hundred sixty-six million, twenty-six thousand, two hundred fifty".