78728642651 has 4 divisors (see below), whose sum is σ = 78733817400. Its totient is φ = 78723467904.

The previous prime is 78728642647. The next prime is 78728642653. The reversal of 78728642651 is 15624682787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15624682787 = 7 ⋅2232097541.

It is a cyclic number.

It is not a de Polignac number, because 78728642651 - 2² = 78728642647 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78728642653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2564486 + ... + 2595003.

It is an arithmetic number, because the mean of its divisors is an integer number (19683454350).

Almost surely, 2^78728642651 is an apocalyptic number.

78728642651 is a deficient number, since it is larger than the sum of its proper divisors (5174749).

78728642651 is a wasteful number, since it uses less digits than its factorization.

78728642651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5174748.

The product of its digits is 9031680, while the sum is 56.

The spelling of 78728642651 in words is "seventy-eight billion, seven hundred twenty-eight million, six hundred forty-two thousand, six hundred fifty-one".