19856949840 has 480 divisors, whose sum is σ = 84303937536. Its totient is φ = 4075868160.

The previous prime is 19856949821. The next prime is 19856949851. The reversal of 19856949840 is 4894965891.

19856949840 is a `hidden beast` number, since 1 + 9 + 85 + 69 + 498 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 2420145 + ... + 2428335.

Almost surely, 2^19856949840 is an apocalyptic number.

19856949840 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 19856949840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42151968768).

19856949840 is an abundant number, since it is smaller than the sum of its proper divisors (64446987696).

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

19856949840 is a wasteful number, since it uses less digits than its factorization.

19856949840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8267 (or 8258 counting only the distinct ones).

The product of its (nonzero) digits is 22394880, while the sum is 63.

The spelling of 19856949840 in words is "nineteen billion, eight hundred fifty-six million, nine hundred forty-nine thousand, eight hundred forty".