19661921370 has 720 divisors, whose sum is σ = 70480637568. Its totient is φ = 3849431040.

The previous prime is 19661921351. The next prime is 19661921413. The reversal of 19661921370 is 7312916691.

19661921370 is a `hidden beast` number, since 1 + 9 + 6 + 619 + 21 + 3 + 7 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 276928435 + ... + 276928505.

Almost surely, 2^19661921370 is an apocalyptic number.

19661921370 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 19661921370, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35240318784).

19661921370 is an abundant number, since it is smaller than the sum of its proper divisors (50818716198).

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

19661921370 is a wasteful number, since it uses less digits than its factorization.

19661921370 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 118 counting only the distinct ones).

The product of its (nonzero) digits is 122472, while the sum is 45.

The spelling of 19661921370 in words is "nineteen billion, six hundred sixty-one million, nine hundred twenty-one thousand, three hundred seventy".