20781732329 has 4 divisors (see below), whose sum is σ = 20810084676. Its totient is φ = 20753379984.

The previous prime is 20781732287. The next prime is 20781732341. The reversal of 20781732329 is 92323718702.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92323718702 = 2 ⋅46161859351.

It can be written as a sum of positive squares in 2 ways, for example, as 19453275625 + 1328456704 = 139475^2 + 36448^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20781732329 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20781732329.

It is not an unprimeable number, because it can be changed into a prime (20781732529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14175074 + ... + 14176539.

It is an arithmetic number, because the mean of its divisors is an integer number (5202521169).

Almost surely, 2^20781732329 is an apocalyptic number.

It is an amenable number.

20781732329 is a deficient number, since it is larger than the sum of its proper divisors (28352347).

20781732329 is an equidigital number, since it uses as much as digits as its factorization.

20781732329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28352346.

The product of its (nonzero) digits is 254016, while the sum is 44.

The spelling of 20781732329 in words is "twenty billion, seven hundred eighty-one million, seven hundred thirty-two thousand, three hundred twenty-nine".