21311132220 has 144 divisors (see below), whose sum is σ = 74569517568. Its totient is φ = 4825560960.

The previous prime is 21311132201. The next prime is 21311132231. The reversal of 21311132220 is 2223111312.

21311132220 is a `hidden beast` number, since 2 + 1 + 311 + 132 + 220 = 666.

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 = 21311132193 and 21311132202.

It is a congruent number.

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, 55785 + ... + 213855.

It is an arithmetic number, because the mean of its divisors is an integer number (517843872).

Almost surely, 2^21311132220 is an apocalyptic number.

21311132220 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 21311132220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37284758784).

21311132220 is an abundant number, since it is smaller than the sum of its proper divisors (53258385348).

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

21311132220 is a wasteful number, since it uses less digits than its factorization.

21311132220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158200 (or 158195 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

Adding to 21311132220 its reverse (2223111312), we get a palindrome (23534243532).

The spelling of 21311132220 in words is "twenty-one billion, three hundred eleven million, one hundred thirty-two thousand, two hundred twenty".