78391213 has 2 divisors, whose sum is σ = 78391214. Its totient is φ = 78391212.

The previous prime is 78391211. The next prime is 78391217. The reversal of 78391213 is 31219387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77387209 + 1004004 = 8797^2 + 1002^2 .

It is a cyclic number.

It is not a de Polignac number, because 78391213 - 2¹ = 78391211 is a prime.

It is a super-2 number, since 2×78391213² = 12290364551222738, which contains 22 as substring.

Together with 78391211, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78391211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39195606 + 39195607.

It is an arithmetic number, because the mean of its divisors is an integer number (39195607).

Almost surely, 2^78391213 is an apocalyptic number.

It is an amenable number.

78391213 is a deficient number, since it is larger than the sum of its proper divisors (1).

78391213 is an equidigital number, since it uses as much as digits as its factorization.

78391213 is an evil number, because the sum of its binary digits is even.

The product of its digits is 9072, while the sum is 34.

The square root of 78391213 is about 8853.8812393210. The cubic root of 78391213 is about 427.9790018667.

The spelling of 78391213 in words is "seventy-eight million, three hundred ninety-one thousand, two hundred thirteen".