19726520978 has 16 divisors (see below), whose sum is σ = 30317051520. Its totient is φ = 9620925600.

The previous prime is 19726520971. The next prime is 19726520981. The reversal of 19726520978 is 87902562791.

It is not an unprimeable number, because it can be changed into a prime (19726520971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 502523 + ... + 540353.

It is an arithmetic number, because the mean of its divisors is an integer number (1894815720).

Almost surely, 2^19726520978 is an apocalyptic number.

19726520978 is a deficient number, since it is larger than the sum of its proper divisors (10590530542).

19726520978 is a wasteful number, since it uses less digits than its factorization.

19726520978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44233.

The product of its (nonzero) digits is 3810240, while the sum is 56.

The spelling of 19726520978 in words is "nineteen billion, seven hundred twenty-six million, five hundred twenty thousand, nine hundred seventy-eight".