19864799978 has 8 divisors (see below), whose sum is σ = 29885619972. Its totient is φ = 9902926656.

The previous prime is 19864799971. The next prime is 19864800049. The reversal of 19864799978 is 87999746891.

It can be written as a sum of positive squares in 2 ways, for example, as 19860419329 + 4380649 = 140927^2 + 2093^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×19864799978² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19864799899 and 19864799908.

It is not an unprimeable number, because it can be changed into a prime (19864799971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14735825 + ... + 14737172.

Almost surely, 2^19864799978 is an apocalyptic number.

19864799978 is a deficient number, since it is larger than the sum of its proper divisors (10020819994).

19864799978 is a wasteful number, since it uses less digits than its factorization.

19864799978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29473336.

The product of its digits is 493807104, while the sum is 77.

The spelling of 19864799978 in words is "nineteen billion, eight hundred sixty-four million, seven hundred ninety-nine thousand, nine hundred seventy-eight".