21785007220 has 12 divisors (see below), whose sum is σ = 45748515204. Its totient is φ = 8714002880.

The previous prime is 21785007217. The next prime is 21785007259. The reversal of 21785007220 is 2270058712.

It can be written as a sum of positive squares in 2 ways, for example, as 4069929616 + 17715077604 = 63796^2 + 133098^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 544625161 + ... + 544625200.

It is an arithmetic number, because the mean of its divisors is an integer number (3812376267).

Almost surely, 2^21785007220 is an apocalyptic number.

21785007220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21785007220 is an abundant number, since it is smaller than the sum of its proper divisors (23963507984).

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

21785007220 is a wasteful number, since it uses less digits than its factorization.

21785007220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1089250370 (or 1089250368 counting only the distinct ones).

The product of its (nonzero) digits is 15680, while the sum is 34.

The spelling of 21785007220 in words is "twenty-one billion, seven hundred eighty-five million, seven thousand, two hundred twenty".