78500726921 has 2 divisors, whose sum is σ = 78500726922. Its totient is φ = 78500726920.

The previous prime is 78500726897. The next prime is 78500726929. The reversal of 78500726921 is 12962700587.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78467214400 + 33512521 = 280120^2 + 5789^2 .

It is an emirp because it is prime and its reverse (12962700587) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78500726921 is a prime.

It is not a weakly prime, because it can be changed into another prime (78500726929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39250363460 + 39250363461.

It is an arithmetic number, because the mean of its divisors is an integer number (39250363461).

Almost surely, 2^78500726921 is an apocalyptic number.

It is an amenable number.

78500726921 is a deficient number, since it is larger than the sum of its proper divisors (1).

78500726921 is an equidigital number, since it uses as much as digits as its factorization.

78500726921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 423360, while the sum is 47.

The spelling of 78500726921 in words is "seventy-eight billion, five hundred million, seven hundred twenty-six thousand, nine hundred twenty-one".