78668045221 has 2 divisors, whose sum is σ = 78668045222. Its totient is φ = 78668045220.

The previous prime is 78668045219. The next prime is 78668045297. The reversal of 78668045221 is 12254086687.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 68374928196 + 10293117025 = 261486^2 + 101455^2 .

It is a cyclic number.

It is not a de Polignac number, because 78668045221 - 2¹ = 78668045219 is a prime.

It is a super-2 number, since 2×78668045221² (a number of 23 digits) contains 22 as substring.

Together with 78668045219, 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 (78668045021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39334022610 + 39334022611.

It is an arithmetic number, because the mean of its divisors is an integer number (39334022611).

Almost surely, 2^78668045221 is an apocalyptic number.

It is an amenable number.

78668045221 is a deficient number, since it is larger than the sum of its proper divisors (1).

78668045221 is an equidigital number, since it uses as much as digits as its factorization.

78668045221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1290240, while the sum is 49.

The spelling of 78668045221 in words is "seventy-eight billion, six hundred sixty-eight million, forty-five thousand, two hundred twenty-one".