78724409 has 4 divisors (see below), whose sum is σ = 79062516. Its totient is φ = 78386304.

The previous prime is 78724361. The next prime is 78724411. The reversal of 78724409 is 90442787.

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 40284409 + 38440000 = 6347^2 + 6200^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78724409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78724109) 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, 168704 + ... + 169169.

It is an arithmetic number, because the mean of its divisors is an integer number (19765629).

Almost surely, 2^78724409 is an apocalyptic number.

It is an amenable number.

78724409 is a deficient number, since it is larger than the sum of its proper divisors (338107).

78724409 is a wasteful number, since it uses less digits than its factorization.

78724409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338106.

The product of its (nonzero) digits is 112896, while the sum is 41.

The square root of 78724409 is about 8872.6776679873. The cubic root of 78724409 is about 428.5845090558.

The spelling of 78724409 in words is "seventy-eight million, seven hundred twenty-four thousand, four hundred nine".