21279516804 has 288 divisors, whose sum is σ = 69295000320. Its totient is φ = 5559902208.

The previous prime is 21279516799. The next prime is 21279516857. The reversal of 21279516804 is 40861597212.

21279516804 is a `hidden beast` number, since 2 + 127 + 9 + 516 + 8 + 0 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21279516804.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 9994012 + ... + 9996140.

It is an arithmetic number, because the mean of its divisors is an integer number (240607640).

Almost surely, 2^21279516804 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21279516804, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34647500160).

21279516804 is an abundant number, since it is smaller than the sum of its proper divisors (48015483516).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21279516804 is a wasteful number, since it uses less digits than its factorization.

21279516804 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2281 (or 2267 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The spelling of 21279516804 in words is "twenty-one billion, two hundred seventy-nine million, five hundred sixteen thousand, eight hundred four".