21131220312 has 48 divisors (see below), whose sum is σ = 57239938080. Its totient is φ = 7042564800.

The previous prime is 21131220311. The next prime is 21131220361. The reversal of 21131220312 is 21302213112.

21131220312 is a `hidden beast` number, since 2 + 1 + 131 + 220 + 312 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21131220311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 482362 + ... + 524342.

It is an arithmetic number, because the mean of its divisors is an integer number (1192498710).

Almost surely, 2^21131220312 is an apocalyptic number.

It is an amenable number.

21131220312 is an abundant number, since it is smaller than the sum of its proper divisors (36108717768).

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

21131220312 is a wasteful number, since it uses less digits than its factorization.

21131220312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48984 (or 48977 counting only the distinct ones).

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

Adding to 21131220312 its reverse (21302213112), we get a palindrome (42433433424).

The spelling of 21131220312 in words is "twenty-one billion, one hundred thirty-one million, two hundred twenty thousand, three hundred twelve".