21210121200020 has 24 divisors (see below), whose sum is σ = 44548807973544. Its totient is φ = 8482609726976.

The previous prime is 21210121199963. The next prime is 21210121200031. The reversal of 21210121200020 is 2000212101212.

It can be written as a sum of positive squares in 4 ways, for example, as 7005529065616 + 14204592134404 = 2646796^2 + 3768898^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21210121199968 and 21210121200004.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89801177 + ... + 90037056.

It is an arithmetic number, because the mean of its divisors is an integer number (1856200332231).

Almost surely, 2^{21210121200020} is an apocalyptic number.

21210121200020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21210121200020 is an abundant number, since it is smaller than the sum of its proper divisors (23338686773524).

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

21210121200020 is a wasteful number, since it uses less digits than its factorization.

21210121200020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 179844139 (or 179844137 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 14.

Adding to 21210121200020 its reverse (2000212101212), we get a palindrome (23210333301232).

The spelling of 21210121200020 in words is "twenty-one trillion, two hundred ten billion, one hundred twenty-one million, two hundred thousand, twenty".