21598983821 has 2 divisors, whose sum is σ = 21598983822. Its totient is φ = 21598983820.

The previous prime is 21598983787. The next prime is 21598983829. The reversal of 21598983821 is 12838989512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13067690596 + 8531293225 = 114314^2 + 92365^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21598983821 is a prime.

It is a super-2 number, since 2×21598983821² (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 (21598983829) 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 as a sum of consecutive naturals, namely, 10799491910 + 10799491911.

It is an arithmetic number, because the mean of its divisors is an integer number (10799491911).

Almost surely, 2^21598983821 is an apocalyptic number.

It is an amenable number.

21598983821 is a deficient number, since it is larger than the sum of its proper divisors (1).

21598983821 is an equidigital number, since it uses as much as digits as its factorization.

21598983821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2488320, while the sum is 56.

The spelling of 21598983821 in words is "twenty-one billion, five hundred ninety-eight million, nine hundred eighty-three thousand, eight hundred twenty-one".