19961640000 has 700 divisors, whose sum is σ = 75898289148. Its totient is φ = 5184000000.

The previous prime is 19961639959. The next prime is 19961640047. The reversal of 19961640000 is 4616991.

19961640000 is a `hidden beast` number, since 1 + 9 + 9 + 6 + 1 + 640 + 0 + 0 + 0 = 666.

It can be written as a sum of positive squares in 10 ways, for example, as 15497262144 + 4464377856 = 124488^2 + 66816^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 99 ways as a sum of consecutive naturals, for example, 197639950 + ... + 197640050.

Almost surely, 2^19961640000 is an apocalyptic number.

19961640000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19961640000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37949144574).

19961640000 is an abundant number, since it is smaller than the sum of its proper divisors (55936649148).

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

19961640000 is an equidigital number, since it uses as much as digits as its factorization.

19961640000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 36.

The spelling of 19961640000 in words is "nineteen billion, nine hundred sixty-one million, six hundred forty thousand".