20644723399 has 16 divisors (see below), whose sum is σ = 21562347744. Its totient is φ = 19747353600.

The previous prime is 20644723397. The next prime is 20644723441. The reversal of 20644723399 is 99332744602.

It is a cyclic number.

It is not a de Polignac number, because 20644723399 - 2¹ = 20644723397 is a prime.

It is a super-2 number, since 2×20644723399² (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 (20644723397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4524079 + ... + 4528639.

It is an arithmetic number, because the mean of its divisors is an integer number (1347646734).

Almost surely, 2^20644723399 is an apocalyptic number.

20644723399 is a deficient number, since it is larger than the sum of its proper divisors (917624345).

20644723399 is a wasteful number, since it uses less digits than its factorization.

20644723399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6738.

The product of its (nonzero) digits is 1959552, while the sum is 49.

The spelling of 20644723399 in words is "twenty billion, six hundred forty-four million, seven hundred twenty-three thousand, three hundred ninety-nine".