21121212120020 has 12 divisors (see below), whose sum is σ = 44354545452084. Its totient is φ = 8448484848000.

The previous prime is 21121212119989. The next prime is 21121212120049. The reversal of 21121212120020 is 2002121212112.

It can be written as a sum of positive squares in 2 ways, for example, as 13358279390404 + 7762932729616 = 3654898^2 + 2786204^2 .

It is a super-2 number, since 2×21121212120020² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 528030302981 + ... + 528030303020.

It is an arithmetic number, because the mean of its divisors is an integer number (3696212121007).

Almost surely, 2^{21121212120020} is an apocalyptic number.

21121212120020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21121212120020 is an abundant number, since it is smaller than the sum of its proper divisors (23233333332064).

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

21121212120020 is a wasteful number, since it uses less digits than its factorization.

21121212120020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1056060606010 (or 1056060606008 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 21121212120020 its reverse (2002121212112), we get a palindrome (23123333332132).

The spelling of 21121212120020 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, one hundred twenty thousand, twenty".