78316421 has 4 divisors (see below), whose sum is σ = 78428844. Its totient is φ = 78204000.

The previous prime is 78316417. The next prime is 78316439. The reversal of 78316421 is 12461387.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 34093921 + 44222500 = 5839^2 + 6650^2 .

It is a cyclic number.

It is not a de Polignac number, because 78316421 - 2² = 78316417 is a prime.

It is a super-2 number, since 2×78316421² = 12266923596498482, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78316411) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55160 + ... + 56561.

It is an arithmetic number, because the mean of its divisors is an integer number (19607211).

Almost surely, 2^78316421 is an apocalyptic number.

It is an amenable number.

78316421 is a deficient number, since it is larger than the sum of its proper divisors (112423).

78316421 is a wasteful number, since it uses less digits than its factorization.

78316421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112422.

The product of its digits is 8064, while the sum is 32.

The square root of 78316421 is about 8849.6565470079. The cubic root of 78316421 is about 427.8428488908.

The spelling of 78316421 in words is "seventy-eight million, three hundred sixteen thousand, four hundred twenty-one".