78243278399 has 32 divisors (see below), whose sum is σ = 93701422080. Its totient is φ = 64393084800.

The previous prime is 78243278381. The next prime is 78243278401. The reversal of 78243278399 is 99387234287.

It is a Cunningham number, because it is equal to 279720²-1.

It is not a de Polignac number, because 78243278399 - 2¹² = 78243274303 is a prime.

It is a super-2 number, since 2×78243278399² (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 (78243278329) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3625589 + ... + 3647105.

It is an arithmetic number, because the mean of its divisors is an integer number (2928169440).

Almost surely, 2^78243278399 is an apocalyptic number.

78243278399 is a deficient number, since it is larger than the sum of its proper divisors (15458143681).

78243278399 is a wasteful number, since it uses less digits than its factorization.

78243278399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22031.

The product of its digits is 36578304, while the sum is 62.

The spelling of 78243278399 in words is "seventy-eight billion, two hundred forty-three million, two hundred seventy-eight thousand, three hundred ninety-nine".