20778066399 has 4 divisors (see below), whose sum is σ = 27704088536. Its totient is φ = 13852044264.

The previous prime is 20778066373. The next prime is 20778066497. The reversal of 20778066399 is 99366087702.

It is a happy number.

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

It is not a de Polignac number, because 20778066399 - 2⁸ = 20778066143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20778066319) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 3463011064 + ... + 3463011069.

It is an arithmetic number, because the mean of its divisors is an integer number (6926022134).

Almost surely, 2^20778066399 is an apocalyptic number.

20778066399 is a deficient number, since it is larger than the sum of its proper divisors (6926022137).

20778066399 is an equidigital number, since it uses as much as digits as its factorization.

20778066399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6926022136.

The product of its (nonzero) digits is 6858432, while the sum is 57.

The spelling of 20778066399 in words is "twenty billion, seven hundred seventy-eight million, sixty-six thousand, three hundred ninety-nine".