20781212729 has 2 divisors, whose sum is σ = 20781212730. Its totient is φ = 20781212728.

The previous prime is 20781212717. The next prime is 20781212773. The reversal of 20781212729 is 92721218702.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14310619129 + 6470593600 = 119627^2 + 80440^2 .

It is a cyclic number.

It is not a de Polignac number, because 20781212729 - 2⁴ = 20781212713 is a prime.

It is not a weakly prime, because it can be changed into another prime (20781212429) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10390606364 + 10390606365.

It is an arithmetic number, because the mean of its divisors is an integer number (10390606365).

Almost surely, 2^20781212729 is an apocalyptic number.

It is an amenable number.

20781212729 is a deficient number, since it is larger than the sum of its proper divisors (1).

20781212729 is an equidigital number, since it uses as much as digits as its factorization.

20781212729 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 56448, while the sum is 41.

The spelling of 20781212729 in words is "twenty billion, seven hundred eighty-one million, two hundred twelve thousand, seven hundred twenty-nine".