78985921 has 4 divisors (see below), whose sum is σ = 90269632. Its totient is φ = 67702212.

The previous prime is 78985919. The next prime is 78985957. The reversal of 78985921 is 12958987.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12958987 = 211 ⋅61417.

It is a cyclic number.

It is not a de Polignac number, because 78985921 - 2¹ = 78985919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78985981) 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 3 ways as a sum of consecutive naturals, for example, 5641845 + ... + 5641858.

It is an arithmetic number, because the mean of its divisors is an integer number (22567408).

Almost surely, 2^78985921 is an apocalyptic number.

It is an amenable number.

78985921 is a deficient number, since it is larger than the sum of its proper divisors (11283711).

78985921 is a wasteful number, since it uses less digits than its factorization.

78985921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11283710.

The product of its digits is 362880, while the sum is 49.

The square root of 78985921 is about 8887.4023763977. The cubic root of 78985921 is about 429.0585514235.

The spelling of 78985921 in words is "seventy-eight million, nine hundred eighty-five thousand, nine hundred twenty-one".