20644540709 has 16 divisors (see below), whose sum is σ = 23025461760. Its totient is φ = 18388312320.

The previous prime is 20644540667. The next prime is 20644540717. The reversal of 20644540709 is 90704544602.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20644540709 is a prime.

It is a super-2 number, since 2×20644540709² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644540729) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 194564 + ... + 281325.

It is an arithmetic number, because the mean of its divisors is an integer number (1439091360).

Almost surely, 2^20644540709 is an apocalyptic number.

It is an amenable number.

20644540709 is a deficient number, since it is larger than the sum of its proper divisors (2380921051).

20644540709 is a wasteful number, since it uses less digits than its factorization.

20644540709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 476020.

The product of its (nonzero) digits is 241920, while the sum is 41.

The spelling of 20644540709 in words is "twenty billion, six hundred forty-four million, five hundred forty thousand, seven hundred nine".