778091994 has 20 divisors (see below), whose sum is σ = 1743502794. Its totient is φ = 259363944.

The previous prime is 778091987. The next prime is 778092013. The reversal of 778091994 is 499190877.

It can be written as a sum of positive squares in only one way, i.e., 725601969 + 52490025 = 26937^2 + 7245^2 .

It is a super-2 number, since 2×778091994² = 1210854302253792072, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a self number, because there is not a number n which added to its sum of digits gives 778091994.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 2401357 + ... + 2401680.

Almost surely, 2^778091994 is an apocalyptic number.

778091994 is an abundant number, since it is smaller than the sum of its proper divisors (965410800).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

778091994 is a wasteful number, since it uses less digits than its factorization.

778091994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4803051 (or 4803042 counting only the distinct ones).

The product of its (nonzero) digits is 1143072, while the sum is 54.

The square root of 778091994 is about 27894.3003855626. The cubic root of 778091994 is about 919.7652181296.

The spelling of 778091994 in words is "seven hundred seventy-eight million, ninety-one thousand, nine hundred ninety-four".