20994255809 has 2 divisors, whose sum is σ = 20994255810. Its totient is φ = 20994255808.

The previous prime is 20994255797. The next prime is 20994255823. The reversal of 20994255809 is 90855249902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18984706225 + 2009549584 = 137785^2 + 44828^2 .

It is a cyclic number.

It is not a de Polignac number, because 20994255809 - 2¹² = 20994251713 is a prime.

It is not a weakly prime, because it can be changed into another prime (20994455809) 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 as a sum of consecutive naturals, namely, 10497127904 + 10497127905.

It is an arithmetic number, because the mean of its divisors is an integer number (10497127905).

Almost surely, 2^20994255809 is an apocalyptic number.

It is an amenable number.

20994255809 is a deficient number, since it is larger than the sum of its proper divisors (1).

20994255809 is an equidigital number, since it uses as much as digits as its factorization.

20994255809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2332800, while the sum is 53.

The spelling of 20994255809 in words is "twenty billion, nine hundred ninety-four million, two hundred fifty-five thousand, eight hundred nine".