20001221212122 has 96 divisors (see below), whose sum is σ = 45961114268160. Its totient is φ = 6277261639680.

The previous prime is 20001221212109. The next prime is 20001221212163. The reversal of 20001221212122 is 22121212210002.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a junction number, because it is equal to n+sod(n) for n = 20001221212095 and 20001221212104.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 61818 + ... + 6325050.

It is an arithmetic number, because the mean of its divisors is an integer number (478761606960).

Almost surely, 2^{20001221212122} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20001221212122, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22980557134080).

20001221212122 is an abundant number, since it is smaller than the sum of its proper divisors (25959893056038).

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

20001221212122 is a wasteful number, since it uses less digits than its factorization.

20001221212122 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6263428 (or 6263425 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 20001221212122 its reverse (22121212210002), we get a palindrome (42122433422124).

The spelling of 20001221212122 in words is "twenty trillion, one billion, two hundred twenty-one million, two hundred twelve thousand, one hundred twenty-two".