21643785880 has 32 divisors (see below), whose sum is σ = 48713541840. Its totient is φ = 8654843520.

The previous prime is 21643785853. The next prime is 21643785893. The reversal of 21643785880 is 8858734612.

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, 50470 + ... + 214090.

Almost surely, 2^21643785880 is an apocalyptic number.

21643785880 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21643785880 is an abundant number, since it is smaller than the sum of its proper divisors (27069755960).

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

21643785880 is a wasteful number, since it uses less digits than its factorization.

21643785880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166939 (or 166935 counting only the distinct ones).

The product of its (nonzero) digits is 2580480, while the sum is 52.

The spelling of 21643785880 in words is "twenty-one billion, six hundred forty-three million, seven hundred eighty-five thousand, eight hundred eighty".