78716921 has 4 divisors (see below), whose sum is σ = 78742272. Its totient is φ = 78691572.

The previous prime is 78716917. The next prime is 78716923. The reversal of 78716921 is 12961787.

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.

It is a cyclic number.

It is not a de Polignac number, because 78716921 - 2² = 78716917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78716923) 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, 7241 + ... + 14486.

It is an arithmetic number, because the mean of its divisors is an integer number (19685568).

Almost surely, 2^78716921 is an apocalyptic number.

It is an amenable number.

78716921 is a deficient number, since it is larger than the sum of its proper divisors (25351).

78716921 is a wasteful number, since it uses less digits than its factorization.

78716921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25350.

The product of its digits is 42336, while the sum is 41.

The square root of 78716921 is about 8872.2556883805. The cubic root of 78716921 is about 428.5709201211.

The spelling of 78716921 in words is "seventy-eight million, seven hundred sixteen thousand, nine hundred twenty-one".