19805901978 has 16 divisors (see below), whose sum is σ = 39698487360. Its totient is φ = 6587520096.

The previous prime is 19805901961. The next prime is 19805902049. The reversal of 19805901978 is 87910950891.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3608838 + ... + 3614321.

It is an arithmetic number, because the mean of its divisors is an integer number (2481155460).

Almost surely, 2^19805901978 is an apocalyptic number.

19805901978 is an abundant number, since it is smaller than the sum of its proper divisors (19892585382).

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

19805901978 is a wasteful number, since it uses less digits than its factorization.

19805901978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7223621.

The product of its (nonzero) digits is 1632960, while the sum is 57.

The spelling of 19805901978 in words is "nineteen billion, eight hundred five million, nine hundred one thousand, nine hundred seventy-eight".