78936661 has 4 divisors (see below), whose sum is σ = 83580012. Its totient is φ = 74293312.

The previous prime is 78936629. The next prime is 78936677. The reversal of 78936661 is 16663987.

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

It can be written as a sum of positive squares in 2 ways, for example, as 23716900 + 55219761 = 4870^2 + 7431^2 .

It is a cyclic number.

It is not a de Polignac number, because 78936661 - 2⁵ = 78936629 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78936061) 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, 2321650 + ... + 2321683.

It is an arithmetic number, because the mean of its divisors is an integer number (20895003).

Almost surely, 2^78936661 is an apocalyptic number.

It is an amenable number.

78936661 is a deficient number, since it is larger than the sum of its proper divisors (4643351).

78936661 is a wasteful number, since it uses less digits than its factorization.

78936661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4643350.

The product of its digits is 326592, while the sum is 46.

The square root of 78936661 is about 8884.6306057146. The cubic root of 78936661 is about 428.9693379737.

It can be divided in two parts, 78936 and 661, that added together give a palindrome (79597).

The spelling of 78936661 in words is "seventy-eight million, nine hundred thirty-six thousand, six hundred sixty-one".