15563964780 has 768 divisors, whose sum is σ = 65244856320. Its totient is φ = 2985984000.

The previous prime is 15563964739. The next prime is 15563964799. The reversal of 15563964780 is 8746936551.

15563964780 is a `hidden beast` number, since 1 + 5 + 563 + 9 + 6 + 4 + 78 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 25896480 + ... + 25897080.

It is an arithmetic number, because the mean of its divisors is an integer number (84954240).

Almost surely, 2^15563964780 is an apocalyptic number.

15563964780 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 15563964780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32622428160).

15563964780 is an abundant number, since it is smaller than the sum of its proper divisors (49680891540).

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

15563964780 is a wasteful number, since it uses less digits than its factorization.

15563964780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 687 (or 679 counting only the distinct ones).

The product of its (nonzero) digits is 5443200, while the sum is 54.

It can be divided in two parts, 1556 and 3964780, that added together give a triangular number (3966336 = T₂₈₁₆).

The spelling of 15563964780 in words is "fifteen billion, five hundred sixty-three million, nine hundred sixty-four thousand, seven hundred eighty".