21105505637 has 2 divisors, whose sum is σ = 21105505638. Its totient is φ = 21105505636.

The previous prime is 21105505609. The next prime is 21105505643. The reversal of 21105505637 is 73650550112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20571017476 + 534488161 = 143426^2 + 23119^2 .

It is a cyclic number.

It is not a de Polignac number, because 21105505637 - 2³² = 16810538341 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21105505597 and 21105505606.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21105505607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552752818 + 10552752819.

It is an arithmetic number, because the mean of its divisors is an integer number (10552752819).

Almost surely, 2^21105505637 is an apocalyptic number.

It is an amenable number.

21105505637 is a deficient number, since it is larger than the sum of its proper divisors (1).

21105505637 is an equidigital number, since it uses as much as digits as its factorization.

21105505637 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31500, while the sum is 35.

The spelling of 21105505637 in words is "twenty-one billion, one hundred five million, five hundred five thousand, six hundred thirty-seven".