78077815815 has 32 divisors (see below), whose sum is σ = 133084567296. Its totient is φ = 38951539200.

The previous prime is 78077815807. The next prime is 78077815847. The reversal of 78077815815 is 51851877087.

It is a happy number.

It is not a de Polignac number, because 78077815815 - 2³ = 78077815807 is a prime.

It is a super-2 number, since 2×78077815815² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 897661 + ... + 980790.

It is an arithmetic number, because the mean of its divisors is an integer number (4158892728).

Almost surely, 2^78077815815 is an apocalyptic number.

78077815815 is a deficient number, since it is larger than the sum of its proper divisors (55006751481).

78077815815 is a wasteful number, since it uses less digits than its factorization.

78077815815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878639.

The product of its (nonzero) digits is 4390400, while the sum is 57.

The spelling of 78077815815 in words is "seventy-eight billion, seventy-seven million, eight hundred fifteen thousand, eight hundred fifteen".