21285562809 has 48 divisors (see below), whose sum is σ = 33685467840. Its totient is φ = 11917301760.

The previous prime is 21285562787. The next prime is 21285562817. The reversal of 21285562809 is 90826558212.

It is not a de Polignac number, because 21285562809 - 2⁹ = 21285562297 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21285582809) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 2710729 + ... + 2718569.

It is an arithmetic number, because the mean of its divisors is an integer number (701780580).

Almost surely, 2^21285562809 is an apocalyptic number.

It is an amenable number.

21285562809 is a deficient number, since it is larger than the sum of its proper divisors (12399905031).

21285562809 is a wasteful number, since it uses less digits than its factorization.

21285562809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8230 (or 8223 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 48.

The spelling of 21285562809 in words is "twenty-one billion, two hundred eighty-five million, five hundred sixty-two thousand, eight hundred nine".