21037789369809 has 15 divisors (see below), whose sum is σ = 31426882823083. Its totient is φ = 14025165393024.

The previous prime is 21037789369771. The next prime is 21037789369823. The reversal of 21037789369809 is 90896398773012.

The square root of 21037789369809 is 4586697.

It is a perfect power (a square), and thus also a powerful number.

21037789369809 is a `hidden beast` number, since 2 + 103 + 7 + 7 + 89 + 369 + 80 + 9 = 666.

It can be written as a sum of positive squares in only one way, i.e., 2344895003025 + 18692894366784 = 1531305^2 + 4323528^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21037789369809 is a prime.

It is a super-2 number, since 2×21037789369809² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21037789369109) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 41025457 + ... + 41535089.

Almost surely, 2^{21037789369809} is an apocalyptic number.

21037789369809 is the 4586697-th square number.

21037789369809 is the 2293349-th centered octagonal number.

It is an amenable number.

21037789369809 is a deficient number, since it is larger than the sum of its proper divisors (10389093453274).

21037789369809 is an frugal number, since it uses more digits than its factorization.

21037789369809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1019278 (or 509636 counting only the distinct ones).

The product of its (nonzero) digits is 246903552, while the sum is 72.

The spelling of 21037789369809 in words is "twenty-one trillion, thirty-seven billion, seven hundred eighty-nine million, three hundred sixty-nine thousand, eight hundred nine".