78909615 has 12 divisors (see below), whose sum is σ = 136776744. Its totient is φ = 42085104.

The previous prime is 78909599. The next prime is 78909617. The reversal of 78909615 is 51690987.

It is not a de Polignac number, because 78909615 - 2⁴ = 78909599 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 1753547 = 78909615 / (7 + 8 + 9 + 0 + 9 + 6 + 1 + 5).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78909617) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 876729 + ... + 876818.

It is an arithmetic number, because the mean of its divisors is an integer number (11398062).

Almost surely, 2^78909615 is an apocalyptic number.

78909615 is a deficient number, since it is larger than the sum of its proper divisors (57867129).

78909615 is a wasteful number, since it uses less digits than its factorization.

78909615 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1753558 (or 1753555 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 78909615 is about 8883.1084086597. The cubic root of 78909615 is about 428.9203399126.

It can be divided in two parts, 78909 and 615, that added together give a square (79524 = 282²).

The spelling of 78909615 in words is "seventy-eight million, nine hundred nine thousand, six hundred fifteen".