21212122121220 has 192 divisors, whose sum is σ = 61698669096960. Its totient is φ = 5441238555648.

The previous prime is 21212122121171. The next prime is 21212122121299. The reversal of 21212122121220 is 2212122121212.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1034374207 + ... + 1034394713.

It is an arithmetic number, because the mean of its divisors is an integer number (321347234880).

Almost surely, 2^{21212122121220} is an apocalyptic number.

21212122121220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21212122121220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30849334548480).

21212122121220 is an abundant number, since it is smaller than the sum of its proper divisors (40486546975740).

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

21212122121220 is a wasteful number, since it uses less digits than its factorization.

21212122121220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26842 (or 26840 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

Adding to 21212122121220 its reverse (2212122121212), we get a palindrome (23424244242432).

The spelling of 21212122121220 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty-two million, one hundred twenty-one thousand, two hundred twenty".