21012121222220 has 48 divisors (see below), whose sum is σ = 44170159369728. Its totient is φ = 8396336594880.

The previous prime is 21012121222199. The next prime is 21012121222249. The reversal of 21012121222220 is 2222212121012.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 21012121222192 and 21012121222201.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 104228039 + ... + 104429441.

It is an arithmetic number, because the mean of its divisors is an integer number (920211653536).

Almost surely, 2^{21012121222220} is an apocalyptic number.

21012121222220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012121222220 is an abundant number, since it is smaller than the sum of its proper divisors (23158038147508).

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

21012121222220 is a wasteful number, since it uses less digits than its factorization.

21012121222220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206670 (or 206668 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21012121222220 its reverse (2222212121012), we get a palindrome (23234333343232).

The spelling of 21012121222220 in words is "twenty-one trillion, twelve billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty".