18978605640 has 256 divisors, whose sum is σ = 65349504000. Its totient is φ = 4896460800.

The previous prime is 18978605623. The next prime is 18978605669. The reversal of 18978605640 is 4650687981.

18978605640 is a `hidden beast` number, since 1 + 8 + 9 + 78 + 6 + 0 + 564 + 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 63 ways as a sum of consecutive naturals, for example, 4515540 + ... + 4519740.

It is an arithmetic number, because the mean of its divisors is an integer number (255271500).

Almost surely, 2^18978605640 is an apocalyptic number.

18978605640 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 18978605640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32674752000).

18978605640 is an abundant number, since it is smaller than the sum of its proper divisors (46370898360).

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

18978605640 is a wasteful number, since it uses less digits than its factorization.

18978605640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4357 (or 4347 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The spelling of 18978605640 in words is "eighteen billion, nine hundred seventy-eight million, six hundred five thousand, six hundred forty".