19991494656 has 360 divisors, whose sum is σ = 68513694480. Its totient is φ = 5690621952.

The previous prime is 19991494571. The next prime is 19991494657. The reversal of 19991494656 is 65649419991.

19991494656 is a `hidden beast` number, since 1 + 9 + 9 + 91 + 494 + 6 + 56 = 666.

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

It is a junction number, because it is equal to n+sod(n) for n = 19991494593 and 19991494602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19991494657) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 74317690 + ... + 74317958.

It is an arithmetic number, because the mean of its divisors is an integer number (190315818).

Almost surely, 2^19991494656 is an apocalyptic number.

19991494656 is a gapful number since it is divisible by the number (16) 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 19991494656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34256847240).

19991494656 is an abundant number, since it is smaller than the sum of its proper divisors (48522199824).

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

19991494656 is an frugal number, since it uses more digits than its factorization.

19991494656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 322 (or 281 counting only the distinct ones).

The product of its digits is 18895680, while the sum is 63.

The spelling of 19991494656 in words is "nineteen billion, nine hundred ninety-one million, four hundred ninety-four thousand, six hundred fifty-six".