78821015 has 32 divisors (see below), whose sum is σ = 117573120. Its totient is φ = 49394304.

The previous prime is 78820979. The next prime is 78821047. The reversal of 78821015 is 51012887.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 78821015 - 2¹⁸ = 78558871 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 47876 + ... + 49494.

It is an arithmetic number, because the mean of its divisors is an integer number (3674160).

Almost surely, 2^78821015 is an apocalyptic number.

78821015 is a deficient number, since it is larger than the sum of its proper divisors (38752105).

78821015 is a wasteful number, since it uses less digits than its factorization.

78821015 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1751.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 78821015 is about 8878.1200149581. The cubic root of 78821015 is about 428.7597486925.

The spelling of 78821015 in words is "seventy-eight million, eight hundred twenty-one thousand, fifteen".