19640618391978 has 64 divisors (see below), whose sum is σ = 45554510315520. Its totient is φ = 6260707140336.

The previous prime is 19640618391973. The next prime is 19640618392061. The reversal of 19640618391978 is 87919381604691.

19640618391978 is a `hidden beast` number, since 1 + 96 + 4 + 0 + 61 + 8 + 391 + 97 + 8 = 666.

It is not an unprimeable number, because it can be changed into a prime (19640618391973) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3209851 + ... + 7041617.

It is an arithmetic number, because the mean of its divisors is an integer number (711789223680).

Almost surely, 2^{19640618391978} is an apocalyptic number.

19640618391978 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

19640618391978 is an abundant number, since it is smaller than the sum of its proper divisors (25913891923542).

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

19640618391978 is a wasteful number, since it uses less digits than its factorization.

19640618391978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3835928 (or 3835922 counting only the distinct ones).

The product of its (nonzero) digits is 141087744, while the sum is 72.

The spelling of 19640618391978 in words is "nineteen trillion, six hundred forty billion, six hundred eighteen million, three hundred ninety-one thousand, nine hundred seventy-eight".