21333104581 has 2 divisors, whose sum is σ = 21333104582. Its totient is φ = 21333104580.

The previous prime is 21333104447. The next prime is 21333104593. The reversal of 21333104581 is 18540133312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15096053956 + 6237050625 = 122866^2 + 78975^2 .

It is a cyclic number.

It is not a de Polignac number, because 21333104581 - 2²¹ = 21331007429 is a prime.

It is a super-2 number, since 2×21333104581² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21333105581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10666552290 + 10666552291.

It is an arithmetic number, because the mean of its divisors is an integer number (10666552291).

Almost surely, 2^21333104581 is an apocalyptic number.

It is an amenable number.

21333104581 is a deficient number, since it is larger than the sum of its proper divisors (1).

21333104581 is an equidigital number, since it uses as much as digits as its factorization.

21333104581 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 31.

Adding to 21333104581 its reverse (18540133312), we get a palindrome (39873237893).

The spelling of 21333104581 in words is "twenty-one billion, three hundred thirty-three million, one hundred four thousand, five hundred eighty-one".