21001002111220 has 36 divisors (see below), whose sum is σ = 44367771413700. Its totient is φ = 8350098821248.

The previous prime is 21001002111203. The next prime is 21001002111251. The reversal of 21001002111220 is 2211120010012.

It can be written as a sum of positive squares in 2 ways, for example, as 15749690713744 + 5251311397476 = 3968588^2 + 2291574^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21001002111220.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18267745 + ... + 19383304.

It is an arithmetic number, because the mean of its divisors is an integer number (1232438094825).

Almost surely, 2^{21001002111220} is an apocalyptic number.

21001002111220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21001002111220 is an abundant number, since it is smaller than the sum of its proper divisors (23366769302480).

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

21001002111220 is a wasteful number, since it uses less digits than its factorization.

21001002111220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37651392 (or 37651223 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 13.

Adding to 21001002111220 its reverse (2211120010012), we get a palindrome (23212122121232).

The spelling of 21001002111220 in words is "twenty-one trillion, one billion, two million, one hundred eleven thousand, two hundred twenty".