78387778 has 16 divisors (see below), whose sum is σ = 138714624. Its totient is φ = 32510880.

The previous prime is 78387733. The next prime is 78387781. The reversal of 78387778 is 87778387.

It is a happy number.

It is a super-2 number, since 2×78387778² = 12289287479554568, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89875 + ... + 90742.

It is an arithmetic number, because the mean of its divisors is an integer number (8669664).

Almost surely, 2^78387778 is an apocalyptic number.

78387778 is a deficient number, since it is larger than the sum of its proper divisors (60326846).

78387778 is a wasteful number, since it uses less digits than its factorization.

78387778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180657.

The product of its digits is 3687936, while the sum is 55.

The square root of 78387778 is about 8853.6872544720. The cubic root of 78387778 is about 427.9727506162.

The spelling of 78387778 in words is "seventy-eight million, three hundred eighty-seven thousand, seven hundred seventy-eight".