78386387285821 has 2 divisors, whose sum is σ = 78386387285822. Its totient is φ = 78386387285820.

The previous prime is 78386387285809. The next prime is 78386387285861. The reversal of 78386387285821 is 12858278368387.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 76366538052025 + 2019849233796 = 8738795^2 + 1421214^2 .

It is a cyclic number.

It is not a de Polignac number, because 78386387285821 - 2²⁹ = 78385850414909 is a prime.

It is a super-2 number, since 2×78386387285821² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78386387285861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39193193642910 + 39193193642911.

It is an arithmetic number, because the mean of its divisors is an integer number (39193193642911).

Almost surely, 2^{78386387285821} is an apocalyptic number.

It is an amenable number.

78386387285821 is a deficient number, since it is larger than the sum of its proper divisors (1).

78386387285821 is an equidigital number, since it uses as much as digits as its factorization.

78386387285821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1734082560, while the sum is 76.

The spelling of 78386387285821 in words is "seventy-eight trillion, three hundred eighty-six billion, three hundred eighty-seven million, two hundred eighty-five thousand, eight hundred twenty-one".