7778889999 has 16 divisors (see below), whose sum is σ = 11666559840. Its totient is φ = 5185925208.

The previous prime is 7778889983. The next prime is 7778890057. The reversal of 7778889999 is 9999888777.

It is not a de Polignac number, because 7778889999 - 2⁴ = 7778889983 is a prime.

It is a super-2 number, since 2×7778889999² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (81).

It is a plaindrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7778889929) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1776252 + ... + 1780625.

It is an arithmetic number, because the mean of its divisors is an integer number (729159990).

Almost surely, 2^7778889999 is an apocalyptic number.

7778889999 is a deficient number, since it is larger than the sum of its proper divisors (3887669841).

7778889999 is an frugal number, since it uses more digits than its factorization.

7778889999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3556898 (or 3556880 counting only the distinct ones).

The product of its digits is 1152216576, while the sum is 81.

The square root of 7778889999 is about 88198.0158450291. The cubic root of 7778889999 is about 1981.4017553169.

The spelling of 7778889999 in words is "seven billion, seven hundred seventy-eight million, eight hundred eighty-nine thousand, nine hundred ninety-nine".