21531103361 has 2 divisors, whose sum is σ = 21531103362. Its totient is φ = 21531103360.

The previous prime is 21531103261. The next prime is 21531103379. The reversal of 21531103361 is 16330113512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18609052225 + 2922051136 = 136415^2 + 54056^2 .

It is a cyclic number.

It is not a de Polignac number, because 21531103361 - 2¹⁴ = 21531086977 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21531103361.

It is not a weakly prime, because it can be changed into another prime (21531103261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10765551680 + 10765551681.

It is an arithmetic number, because the mean of its divisors is an integer number (10765551681).

Almost surely, 2^21531103361 is an apocalyptic number.

It is an amenable number.

21531103361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21531103361 is an equidigital number, since it uses as much as digits as its factorization.

21531103361 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620, while the sum is 26.

Adding to 21531103361 its reverse (16330113512), we get a palindrome (37861216873).

The spelling of 21531103361 in words is "twenty-one billion, five hundred thirty-one million, one hundred three thousand, three hundred sixty-one".