21801980220 has 24 divisors (see below), whose sum is σ = 61045544784. Its totient is φ = 5813861376.

The previous prime is 21801980183. The next prime is 21801980227. The reversal of 21801980220 is 2208910812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21801980227) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 181683109 + ... + 181683228.

It is an arithmetic number, because the mean of its divisors is an integer number (2543564366).

Almost surely, 2^21801980220 is an apocalyptic number.

21801980220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21801980220 is an abundant number, since it is smaller than the sum of its proper divisors (39243564564).

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

21801980220 is a wasteful number, since it uses less digits than its factorization.

21801980220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 363366349 (or 363366347 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 33.

The spelling of 21801980220 in words is "twenty-one billion, eight hundred one million, nine hundred eighty thousand, two hundred twenty".