6644778888779 has 2 divisors, whose sum is σ = 6644778888780. Its totient is φ = 6644778888778.

The previous prime is 6644778888773. The next prime is 6644778888973. The reversal of 6644778888779 is 9778888774466.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6644778888779 is a prime.

It is a super-2 number, since 2×6644778888779² (a number of 26 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 6644778888694 and 6644778888703.

It is not a weakly prime, because it can be changed into another prime (6644778888773) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3322389444389 + 3322389444390.

It is an arithmetic number, because the mean of its divisors is an integer number (3322389444390).

Almost surely, 2^{6644778888779} is an apocalyptic number.

6644778888779 is a deficient number, since it is larger than the sum of its proper divisors (1).

6644778888779 is an equidigital number, since it uses as much as digits as its factorization.

6644778888779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 50982027264, while the sum is 89.

The spelling of 6644778888779 in words is "six trillion, six hundred forty-four billion, seven hundred seventy-eight million, eight hundred eighty-eight thousand, seven hundred seventy-nine".