21304816165808 has 40 divisors (see below), whose sum is σ = 47183813875968. Its totient is φ = 9128919926592.

The previous prime is 21304816165783. The next prime is 21304816165813. The reversal of 21304816165808 is 80856161840312.

21304816165808 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 21304816165808.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17271716 + ... + 18464067.

Almost surely, 2^{21304816165808} is an apocalyptic number.

21304816165808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21304816165808 is an abundant number, since it is smaller than the sum of its proper divisors (25878997710160).

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

21304816165808 is a wasteful number, since it uses less digits than its factorization.

21304816165808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35741121 (or 35741115 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 53.

The spelling of 21304816165808 in words is "twenty-one trillion, three hundred four billion, eight hundred sixteen million, one hundred sixty-five thousand, eight hundred eight".