78918221 has 8 divisors (see below), whose sum is σ = 82579200. Its totient is φ = 75276432.

The previous prime is 78918173. The next prime is 78918227. The reversal of 78918221 is 12281987.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 78918221 - 2¹⁸ = 78656077 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78918227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3980 + ... + 13178.

It is an arithmetic number, because the mean of its divisors is an integer number (10322400).

Almost surely, 2^78918221 is an apocalyptic number.

It is an amenable number.

78918221 is a deficient number, since it is larger than the sum of its proper divisors (3660979).

78918221 is a wasteful number, since it uses less digits than its factorization.

78918221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9595.

The product of its digits is 16128, while the sum is 38.

The square root of 78918221 is about 8883.5927979619. The cubic root of 78918221 is about 428.9359322425.

The spelling of 78918221 in words is "seventy-eight million, nine hundred eighteen thousand, two hundred twenty-one".