78721282057 has 4 divisors (see below), whose sum is σ = 85877762256. Its totient is φ = 71564801860.

The previous prime is 78721282009. The next prime is 78721282063. The reversal of 78721282057 is 75028212787.

It is a happy number.

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 not a de Polignac number, because 78721282057 - 2¹⁹ = 78720757769 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 78721282057.

It is not an unprimeable number, because it can be changed into a prime (78721282007) 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, 3578240083 + ... + 3578240104.

It is an arithmetic number, because the mean of its divisors is an integer number (21469440564).

Almost surely, 2^78721282057 is an apocalyptic number.

It is an amenable number.

78721282057 is a deficient number, since it is larger than the sum of its proper divisors (7156480199).

78721282057 is a wasteful number, since it uses less digits than its factorization.

78721282057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7156480198.

The product of its (nonzero) digits is 878080, while the sum is 49.

The spelling of 78721282057 in words is "seventy-eight billion, seven hundred twenty-one million, two hundred eighty-two thousand, fifty-seven".