78540709 has 4 divisors (see below), whose sum is σ = 84582316. Its totient is φ = 72499104.

The previous prime is 78540703. The next prime is 78540719. The reversal of 78540709 is 90704587.

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 39727809 + 38812900 = 6303^2 + 6230^2 .

It is a cyclic number.

It is not a de Polignac number, because 78540709 - 2¹¹ = 78538661 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78540703) 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, 3020784 + ... + 3020809.

It is an arithmetic number, because the mean of its divisors is an integer number (21145579).

Almost surely, 2^78540709 is an apocalyptic number.

It is an amenable number.

78540709 is a deficient number, since it is larger than the sum of its proper divisors (6041607).

78540709 is a wasteful number, since it uses less digits than its factorization.

78540709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6041606.

The product of its (nonzero) digits is 70560, while the sum is 40.

The square root of 78540709 is about 8862.3196173462. The cubic root of 78540709 is about 428.2508882925.

The spelling of 78540709 in words is "seventy-eight million, five hundred forty thousand, seven hundred nine".