8640561542778 has 24 divisors (see below), whose sum is σ = 20423145465216. Its totient is φ = 2618351982600.

The previous prime is 8640561542773. The next prime is 8640561542807. The reversal of 8640561542778 is 8772451650468.

8640561542778 is a `hidden beast` number, since 8 + 6 + 4 + 0 + 5 + 615 + 4 + 2 + 7 + 7 + 8 = 666.

It is a Smith number, since the sum of its digits (63) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (8640561542773) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21819599658 + ... + 21819600053.

It is an arithmetic number, because the mean of its divisors is an integer number (850964394384).

Almost surely, 2^{8640561542778} is an apocalyptic number.

8640561542778 is an abundant number, since it is smaller than the sum of its proper divisors (11782583922438).

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

8640561542778 is a wasteful number, since it uses less digits than its factorization.

8640561542778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43639199730 (or 43639199727 counting only the distinct ones).

The product of its (nonzero) digits is 90316800, while the sum is 63.

The spelling of 8640561542778 in words is "eight trillion, six hundred forty billion, five hundred sixty-one million, five hundred forty-two thousand, seven hundred seventy-eight".