21220131220 has 24 divisors (see below), whose sum is σ = 45766662984. Its totient is φ = 8258645376.

The previous prime is 21220131211. The next prime is 21220131239. The reversal of 21220131220 is 2213102212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 6957561744 + 14262569476 = 83412^2 + 119426^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21220131194 and 21220131203.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14337187 + ... + 14338666.

It is an arithmetic number, because the mean of its divisors is an integer number (1906944291).

Almost surely, 2^21220131220 is an apocalyptic number.

21220131220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21220131220 is an abundant number, since it is smaller than the sum of its proper divisors (24546531764).

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

21220131220 is a wasteful number, since it uses less digits than its factorization.

21220131220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28675899 (or 28675897 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

Adding to 21220131220 its reverse (2213102212), we get a palindrome (23433233432).

The spelling of 21220131220 in words is "twenty-one billion, two hundred twenty million, one hundred thirty-one thousand, two hundred twenty".