19656025978 has 4 divisors (see below), whose sum is σ = 29484038970. Its totient is φ = 9828012988.

The previous prime is 19656025927. The next prime is 19656025981. The reversal of 19656025978 is 87952065691.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19628850609 + 27175369 = 140103^2 + 5213^2 .

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4914006493 + ... + 4914006496.

Almost surely, 2^19656025978 is an apocalyptic number.

19656025978 is a deficient number, since it is larger than the sum of its proper divisors (9828012992).

19656025978 is an equidigital number, since it uses as much as digits as its factorization.

19656025978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9828012991.

The product of its (nonzero) digits is 8164800, while the sum is 58.

The spelling of 19656025978 in words is "nineteen billion, six hundred fifty-six million, twenty-five thousand, nine hundred seventy-eight".