21073831609 has 2 divisors, whose sum is σ = 21073831610. Its totient is φ = 21073831608.

The previous prime is 21073831529. The next prime is 21073831619. The reversal of 21073831609 is 90613837012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20310525225 + 763306384 = 142515^2 + 27628^2 .

It is a cyclic number.

It is not a de Polignac number, because 21073831609 - 2²³ = 21065443001 is a prime.

It is not a weakly prime, because it can be changed into another prime (21073831619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10536915804 + 10536915805.

It is an arithmetic number, because the mean of its divisors is an integer number (10536915805).

Almost surely, 2^21073831609 is an apocalyptic number.

It is an amenable number.

21073831609 is a deficient number, since it is larger than the sum of its proper divisors (1).

21073831609 is an equidigital number, since it uses as much as digits as its factorization.

21073831609 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 54432, while the sum is 40.

The spelling of 21073831609 in words is "twenty-one billion, seventy-three million, eight hundred thirty-one thousand, six hundred nine".