21108138562 has 24 divisors (see below), whose sum is σ = 36940898124. Its totient is φ = 9019487232.

The previous prime is 21108138551. The next prime is 21108138593. The reversal of 21108138562 is 26583180112.

It can be written as a sum of positive squares in 2 ways, for example, as 20767403881 + 340734681 = 144109^2 + 18459^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 286543 + ... + 352594.

Almost surely, 2^21108138562 is an apocalyptic number.

21108138562 is a deficient number, since it is larger than the sum of its proper divisors (15832759562).

21108138562 is a wasteful number, since it uses less digits than its factorization.

21108138562 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 639490 (or 639483 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 37.

The spelling of 21108138562 in words is "twenty-one billion, one hundred eight million, one hundred thirty-eight thousand, five hundred sixty-two".