77999978 has 64 divisors (see below), whose sum is σ = 152616960. Its totient is φ = 29092608.

The previous prime is 77999951. The next prime is 78000001. The reversal of 77999978 is 87999977.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 212351 + ... + 212717.

It is an arithmetic number, because the mean of its divisors is an integer number (2384640).

Almost surely, 2^77999978 is an apocalyptic number.

77999978 is a deficient number, since it is larger than the sum of its proper divisors (74616982).

77999978 is a wasteful number, since it uses less digits than its factorization.

77999978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 459.

The product of its digits is 18003384, while the sum is 65.

The square root of 77999978 is about 8831.7596208230. The cubic root of 77999978 is about 427.2658279995.

Subtracting 77999978 from its reverse (87999977), we obtain a palindrome (9999999).

The spelling of 77999978 in words is "seventy-seven million, nine hundred ninety-nine thousand, nine hundred seventy-eight".