21809656888 has 32 divisors (see below), whose sum is σ = 41173462800. Its totient is φ = 10830163968.

The previous prime is 21809656871. The next prime is 21809656903. The reversal of 21809656888 is 88865690812.

It is a super-2 number, since 2×21809656888² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

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, 2098168 + ... + 2108536.

Almost surely, 2^21809656888 is an apocalyptic number.

It is an amenable number.

21809656888 is a deficient number, since it is larger than the sum of its proper divisors (19363805912).

21809656888 is a wasteful number, since it uses less digits than its factorization.

21809656888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12151 (or 12147 counting only the distinct ones).

The product of its (nonzero) digits is 13271040, while the sum is 61.

The spelling of 21809656888 in words is "twenty-one billion, eight hundred nine million, six hundred fifty-six thousand, eight hundred eighty-eight".