21131222220 has 192 divisors, whose sum is σ = 66342460800. Its totient is φ = 5583790080.

The previous prime is 21131222213. The next prime is 21131222251. The reversal of 21131222220 is 2222213112.

It is a super-2 number, since 2×21131222220² (a number of 21 digits) contains 22 as substring.

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 = 21131222193 and 21131222202.

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, 51665376 + ... + 51665784.

It is an arithmetic number, because the mean of its divisors is an integer number (345533650).

Almost surely, 2^21131222220 is an apocalyptic number.

21131222220 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 21131222220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33171230400).

21131222220 is an abundant number, since it is smaller than the sum of its proper divisors (45211238580).

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

21131222220 is a wasteful number, since it uses less digits than its factorization.

21131222220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1065 (or 1057 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

Adding to 21131222220 its reverse (2222213112), we get a palindrome (23353435332).

The spelling of 21131222220 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty-two thousand, two hundred twenty".