78999779 has 4 divisors (see below), whose sum is σ = 82434576. Its totient is φ = 75564984.

The previous prime is 78999737. The next prime is 78999787. The reversal of 78999779 is 97799987.

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

It is a cyclic number.

It is not a de Polignac number, because 78999779 - 2⁸ = 78999523 is a prime.

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 3 ways as a sum of consecutive naturals, for example, 1717364 + ... + 1717409.

It is an arithmetic number, because the mean of its divisors is an integer number (20608644).

Almost surely, 2^78999779 is an apocalyptic number.

78999779 is a deficient number, since it is larger than the sum of its proper divisors (3434797).

78999779 is a wasteful number, since it uses less digits than its factorization.

78999779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3434796.

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

The square root of 78999779 is about 8888.1819850856. The cubic root of 78999779 is about 429.0836425859.

The spelling of 78999779 in words is "seventy-eight million, nine hundred ninety-nine thousand, seven hundred seventy-nine".