78644978 has 4 divisors (see below), whose sum is σ = 117967470. Its totient is φ = 39322488.

The previous prime is 78644957. The next prime is 78644983. The reversal of 78644978 is 87944687.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 50310649 + 28334329 = 7093^2 + 5323^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19661243 + ... + 19661246.

Almost surely, 2^78644978 is an apocalyptic number.

78644978 is a deficient number, since it is larger than the sum of its proper divisors (39322492).

78644978 is a wasteful number, since it uses less digits than its factorization.

78644978 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39322491.

The product of its digits is 2709504, while the sum is 53.

The square root of 78644978 is about 8868.2003811371. The cubic root of 78644978 is about 428.4403167929.

The spelling of 78644978 in words is "seventy-eight million, six hundred forty-four thousand, nine hundred seventy-eight".