2126921809609 has 3 divisors (see below), whose sum is σ = 2126923268007. Its totient is φ = 2126920351212.

The previous prime is 2126921809583. The next prime is 2126921809651. The reversal of 2126921809609 is 9069081296212.

The square root of 2126921809609 is 1458397.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 1940100765625 + 186821043984 = 1392875^2 + 432228^2 .

It is not a de Polignac number, because 2126921809609 - 2²⁹ = 2126384938697 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 2126921809609.

It is not an unprimeable number, because it can be changed into a prime (2126921809409) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 729199 + ... + 2187595.

It is an arithmetic number, because the mean of its divisors is an integer number (708974422669).

Almost surely, 2^{2126921809609} is an apocalyptic number.

2126921809609 is the 1458397-th square number.

2126921809609 is the 729199-th centered octagonal number.

It is an amenable number.

2126921809609 is a deficient number, since it is larger than the sum of its proper divisors (1458398).

2126921809609 is an frugal number, since it uses more digits than its factorization.

2126921809609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2916794 (or 1458397 counting only the distinct ones).

The product of its (nonzero) digits is 1679616, while the sum is 55.

The spelling of 2126921809609 in words is "two trillion, one hundred twenty-six billion, nine hundred twenty-one million, eight hundred nine thousand, six hundred nine".