78999978 has 16 divisors (see below), whose sum is σ = 159565536. Its totient is φ = 26072400.

The previous prime is 78999961. The next prime is 78999979. The reversal of 78999978 is 87999987.

It is not an unprimeable number, because it can be changed into a prime (78999979) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 64576 + ... + 65787.

It is an arithmetic number, because the mean of its divisors is an integer number (9972846).

Almost surely, 2^78999978 is an apocalyptic number.

78999978 is an abundant number, since it is smaller than the sum of its proper divisors (80565558).

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

78999978 is a wasteful number, since it uses less digits than its factorization.

78999978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 130469.

The product of its digits is 20575296, while the sum is 66.

The square root of 78999978 is about 8888.1931797188. The cubic root of 78999978 is about 429.0840028720.

Subtracting 78999978 from its reverse (87999987), we obtain a palindrome (9000009).

The spelling of 78999978 in words is "seventy-eight million, nine hundred ninety-nine thousand, nine hundred seventy-eight".