78115385221 has 4 divisors (see below), whose sum is σ = 78164178444. Its totient is φ = 78066592000.

The previous prime is 78115385219. The next prime is 78115385389. The reversal of 78115385221 is 12258351187.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 51297720100 + 26817665121 = 226490^2 + 163761^2 .

It is a cyclic number.

It is not a de Polignac number, because 78115385221 - 2¹ = 78115385219 is a prime.

It is a super-2 number, since 2×78115385221² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78115385521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24394210 + ... + 24397411.

It is an arithmetic number, because the mean of its divisors is an integer number (19541044611).

Almost surely, 2^78115385221 is an apocalyptic number.

It is an amenable number.

78115385221 is a deficient number, since it is larger than the sum of its proper divisors (48793223).

78115385221 is a wasteful number, since it uses less digits than its factorization.

78115385221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48793222.

The product of its digits is 134400, while the sum is 43.

The spelling of 78115385221 in words is "seventy-eight billion, one hundred fifteen million, three hundred eighty-five thousand, two hundred twenty-one".