798778219721 has 4 divisors (see below), whose sum is σ = 820366820292. Its totient is φ = 777189619152.

The previous prime is 798778219711. The next prime is 798778219763. The reversal of 798778219721 is 127912877897.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 629745409225 + 169032810496 = 793565^2 + 411136^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-798778219721 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (798778219711) 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, 10794300230 + ... + 10794300303.

It is an arithmetic number, because the mean of its divisors is an integer number (205091705073).

Almost surely, 2^798778219721 is an apocalyptic number.

It is an amenable number.

798778219721 is a deficient number, since it is larger than the sum of its proper divisors (21588600571).

798778219721 is a wasteful number, since it uses less digits than its factorization.

798778219721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21588600570.

The product of its digits is 49787136, while the sum is 68.

The spelling of 798778219721 in words is "seven hundred ninety-eight billion, seven hundred seventy-eight million, two hundred nineteen thousand, seven hundred twenty-one".