21749684860 has 12 divisors (see below), whose sum is σ = 45674338248. Its totient is φ = 8699873936.

The previous prime is 21749684849. The next prime is 21749684861. The reversal of 21749684860 is 6848694712.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21749684861) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 543742102 + ... + 543742141.

It is an arithmetic number, because the mean of its divisors is an integer number (3806194854).

Almost surely, 2^21749684860 is an apocalyptic number.

21749684860 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21749684860 is an abundant number, since it is smaller than the sum of its proper divisors (23924653388).

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

21749684860 is a wasteful number, since it uses less digits than its factorization.

21749684860 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1087484252 (or 1087484250 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 55.

The spelling of 21749684860 in words is "twenty-one billion, seven hundred forty-nine million, six hundred eighty-four thousand, eight hundred sixty".