78102218021 has 2 divisors, whose sum is σ = 78102218022. Its totient is φ = 78102218020.

The previous prime is 78102218011. The next prime is 78102218041. The reversal of 78102218021 is 12081220187.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69311092900 + 8791125121 = 263270^2 + 93761^2 .

It is a cyclic number.

It is not a de Polignac number, because 78102218021 - 2⁶ = 78102217957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78102218011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39051109010 + 39051109011.

It is an arithmetic number, because the mean of its divisors is an integer number (39051109011).

Almost surely, 2^78102218021 is an apocalyptic number.

It is an amenable number.

78102218021 is a deficient number, since it is larger than the sum of its proper divisors (1).

78102218021 is an equidigital number, since it uses as much as digits as its factorization.

78102218021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3584, while the sum is 32.

The spelling of 78102218021 in words is "seventy-eight billion, one hundred two million, two hundred eighteen thousand, twenty-one".