21231202481 has 2 divisors, whose sum is σ = 21231202482. Its totient is φ = 21231202480.

The previous prime is 21231202427. The next prime is 21231202529. The reversal of 21231202481 is 18420213212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15485562481 + 5745640000 = 124441^2 + 75800^2 .

It is a cyclic number.

It is not a de Polignac number, because 21231202481 - 2¹⁰ = 21231201457 is a prime.

It is a super-2 number, since 2×21231202481² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21231202481.

It is not a weakly prime, because it can be changed into another prime (21231202381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10615601240 + 10615601241.

It is an arithmetic number, because the mean of its divisors is an integer number (10615601241).

Almost surely, 2^21231202481 is an apocalyptic number.

It is an amenable number.

21231202481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21231202481 is an equidigital number, since it uses as much as digits as its factorization.

21231202481 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1536, while the sum is 26.

Adding to 21231202481 its reverse (18420213212), we get a palindrome (39651415693).

The spelling of 21231202481 in words is "twenty-one billion, two hundred thirty-one million, two hundred two thousand, four hundred eighty-one".