78888398621 has 2 divisors, whose sum is σ = 78888398622. Its totient is φ = 78888398620.

The previous prime is 78888398609. The next prime is 78888398623. The reversal of 78888398621 is 12689388887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 76468840900 + 2419557721 = 276530^2 + 49189^2 .

It is a cyclic number.

It is not a de Polignac number, because 78888398621 - 2¹⁰ = 78888397597 is a prime.

Together with 78888398623, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78888398623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39444199310 + 39444199311.

It is an arithmetic number, because the mean of its divisors is an integer number (39444199311).

Almost surely, 2^78888398621 is an apocalyptic number.

It is an amenable number.

78888398621 is a deficient number, since it is larger than the sum of its proper divisors (1).

78888398621 is an equidigital number, since it uses as much as digits as its factorization.

78888398621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 74317824, while the sum is 68.

The spelling of 78888398621 in words is "seventy-eight billion, eight hundred eighty-eight million, three hundred ninety-eight thousand, six hundred twenty-one".