78889666 has 4 divisors (see below), whose sum is σ = 118334502. Its totient is φ = 39444832.

The previous prime is 78889633. The next prime is 78889687. The reversal of 78889666 is 66698887.

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., 49999041 + 28890625 = 7071^2 + 5375^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 78889666.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19722415 + ... + 19722418.

Almost surely, 2^78889666 is an apocalyptic number.

78889666 is a deficient number, since it is larger than the sum of its proper divisors (39444836).

78889666 is a wasteful number, since it uses less digits than its factorization.

78889666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39444835.

The product of its digits is 6967296, while the sum is 58.

The square root of 78889666 is about 8881.9854762322. The cubic root of 78889666 is about 428.8841920024.

The spelling of 78889666 in words is "seventy-eight million, eight hundred eighty-nine thousand, six hundred sixty-six".