21003661123220 has 48 divisors (see below), whose sum is σ = 44620328804688. Its totient is φ = 8304345047040.

The previous prime is 21003661123201. The next prime is 21003661123231. The reversal of 21003661123220 is 2232116630012.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 749034859024 + 20254626264196 = 865468^2 + 4500514^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15811301 + ... + 17088140.

It is an arithmetic number, because the mean of its divisors is an integer number (929590183431).

Almost surely, 2^{21003661123220} is an apocalyptic number.

21003661123220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21003661123220 is an abundant number, since it is smaller than the sum of its proper divisors (23616667681468).

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

21003661123220 is a wasteful number, since it uses less digits than its factorization.

21003661123220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32899820 (or 32899818 counting only the distinct ones).

The product of its (nonzero) digits is 5184, while the sum is 29.

Adding to 21003661123220 its reverse (2232116630012), we get a palindrome (23235777753232).

The spelling of 21003661123220 in words is "twenty-one trillion, three billion, six hundred sixty-one million, one hundred twenty-three thousand, two hundred twenty".