78649815 has 16 divisors (see below), whose sum is σ = 127018368. Its totient is φ = 41553696.

The previous prime is 78649787. The next prime is 78649817. The reversal of 78649815 is 51894687.

It is not a de Polignac number, because 78649815 - 2⁵ = 78649783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78649817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 22897 + ... + 26106.

It is an arithmetic number, because the mean of its divisors is an integer number (7938648).

Almost surely, 2^78649815 is an apocalyptic number.

78649815 is a deficient number, since it is larger than the sum of its proper divisors (48368553).

78649815 is a wasteful number, since it uses less digits than its factorization.

78649815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49118.

The product of its digits is 483840, while the sum is 48.

The square root of 78649815 is about 8868.4730929287. The cubic root of 78649815 is about 428.4491002455.

The spelling of 78649815 in words is "seventy-eight million, six hundred forty-nine thousand, eight hundred fifteen".