21000131220 has 48 divisors (see below), whose sum is σ = 58846556160. Its totient is φ = 5595636096.

The previous prime is 21000131171. The next prime is 21000131227. The reversal of 21000131220 is 2213100012.

It is a super-2 number, since 2×21000131220² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a junction number, because it is equal to n+sod(n) for n = 21000131196 and 21000131205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000131227) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 60087 + ... + 213566.

It is an arithmetic number, because the mean of its divisors is an integer number (1225969920).

Almost surely, 2^21000131220 is an apocalyptic number.

21000131220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21000131220 is an abundant number, since it is smaller than the sum of its proper divisors (37846424940).

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

21000131220 is a wasteful number, since it uses less digits than its factorization.

21000131220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 274944 (or 274942 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

Adding to 21000131220 its reverse (2213100012), we get a palindrome (23213231232).

The spelling of 21000131220 in words is "twenty-one billion, one hundred thirty-one thousand, two hundred twenty".