78584921 has 4 divisors (see below), whose sum is σ = 78652644. Its totient is φ = 78517200.

The previous prime is 78584917. The next prime is 78584923. The reversal of 78584921 is 12948587.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12948587 = 29 ⋅446503.

It can be written as a sum of positive squares in 2 ways, for example, as 70744921 + 7840000 = 8411^2 + 2800^2 .

It is a cyclic number.

It is not a de Polignac number, because 78584921 - 2² = 78584917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78584923) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32090 + ... + 34451.

It is an arithmetic number, because the mean of its divisors is an integer number (19663161).

Almost surely, 2^78584921 is an apocalyptic number.

It is an amenable number.

78584921 is a deficient number, since it is larger than the sum of its proper divisors (67723).

78584921 is a wasteful number, since it uses less digits than its factorization.

78584921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67722.

The product of its digits is 161280, while the sum is 44.

The square root of 78584921 is about 8864.8136472235. The cubic root of 78584921 is about 428.3312299688.

The spelling of 78584921 in words is "seventy-eight million, five hundred eighty-four thousand, nine hundred twenty-one".