78378564517 has 4 divisors (see below), whose sum is σ = 85503888576. Its totient is φ = 71253240460.

The previous prime is 78378564493. The next prime is 78378564553. The reversal of 78378564517 is 71546587387.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78378564517 is a prime.

It is a super-2 number, since 2×78378564517² (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 (78378564577) 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, 3562662013 + ... + 3562662034.

It is an arithmetic number, because the mean of its divisors is an integer number (21375972144).

Almost surely, 2^78378564517 is an apocalyptic number.

It is an amenable number.

78378564517 is a deficient number, since it is larger than the sum of its proper divisors (7125324059).

78378564517 is a wasteful number, since it uses less digits than its factorization.

78378564517 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7125324058.

The product of its digits is 39513600, while the sum is 61.

The spelling of 78378564517 in words is "seventy-eight billion, three hundred seventy-eight million, five hundred sixty-four thousand, five hundred seventeen".