81078741643787 has 4 divisors (see below), whose sum is σ = 81204836110440. Its totient is φ = 80952647177136.

The previous prime is 81078741643777. The next prime is 81078741643849. The reversal of 81078741643787 is 78734614787018.

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

It is a cyclic number.

It is not a de Polignac number, because 81078741643787 - 2⁶ = 81078741643723 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81078741643787.

It is not an unprimeable number, because it can be changed into a prime (81078741643777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63047232362 + ... + 63047233647.

It is an arithmetic number, because the mean of its divisors is an integer number (20301209027610).

Almost surely, 2^{81078741643787} is an apocalyptic number.

81078741643787 is a deficient number, since it is larger than the sum of its proper divisors (126094466653).

81078741643787 is a wasteful number, since it uses less digits than its factorization.

81078741643787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 126094466652.

The product of its (nonzero) digits is 354041856, while the sum is 71.

The spelling of 81078741643787 in words is "eighty-one trillion, seventy-eight billion, seven hundred forty-one million, six hundred forty-three thousand, seven hundred eighty-seven".