20853908921 has 2 divisors, whose sum is σ = 20853908922. Its totient is φ = 20853908920.

The previous prime is 20853908863. The next prime is 20853908927. The reversal of 20853908921 is 12980935802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20249290000 + 604618921 = 142300^2 + 24589^2 .

It is a cyclic number.

It is not a de Polignac number, because 20853908921 - 2¹⁰ = 20853907897 is a prime.

It is not a weakly prime, because it can be changed into another prime (20853908927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10426954460 + 10426954461.

It is an arithmetic number, because the mean of its divisors is an integer number (10426954461).

Almost surely, 2^20853908921 is an apocalyptic number.

It is an amenable number.

20853908921 is a deficient number, since it is larger than the sum of its proper divisors (1).

20853908921 is an equidigital number, since it uses as much as digits as its factorization.

20853908921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 311040, while the sum is 47.

The spelling of 20853908921 in words is "twenty billion, eight hundred fifty-three million, nine hundred eight thousand, nine hundred twenty-one".