21231201312 has 216 divisors, whose sum is σ = 64940308524. Its totient is φ = 6576380928.

The previous prime is 21231201301. The next prime is 21231201317. The reversal of 21231201312 is 21310213212.

It can be written as a sum of positive squares in 2 ways, for example, as 17067854736 + 4163346576 = 130644^2 + 64524^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21231201317) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5508378 + ... + 5512230.

Almost surely, 2^21231201312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21231201312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32470154262).

21231201312 is an abundant number, since it is smaller than the sum of its proper divisors (43709107212).

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

21231201312 is a wasteful number, since it uses less digits than its factorization.

21231201312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3960 (or 3930 counting only the distinct ones).

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

Adding to 21231201312 its reverse (21310213212), we get a palindrome (42541414524).

The spelling of 21231201312 in words is "twenty-one billion, two hundred thirty-one million, two hundred one thousand, three hundred twelve".