78721886 has 16 divisors (see below), whose sum is σ = 122629248. Its totient is φ = 37872000.

The previous prime is 78721843. The next prime is 78721891. The reversal of 78721886 is 68812787.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 78721886.

It is a congruent number.

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, 590 + ... + 12561.

It is an arithmetic number, because the mean of its divisors is an integer number (7664328).

Almost surely, 2^78721886 is an apocalyptic number.

78721886 is a deficient number, since it is larger than the sum of its proper divisors (43907362).

78721886 is a wasteful number, since it uses less digits than its factorization.

78721886 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13267.

The product of its digits is 301056, while the sum is 47.

The square root of 78721886 is about 8872.5354887991. The cubic root of 78721886 is about 428.5799305086.

Subtracting from 78721886 its reverse (68812787), we obtain a palindrome (9909099).

The spelling of 78721886 in words is "seventy-eight million, seven hundred twenty-one thousand, eight hundred eighty-six".