20854409 has 2 divisors, whose sum is σ = 20854410. Its totient is φ = 20854408.

The previous prime is 20854397. The next prime is 20854411. The reversal of 20854409 is 90445802.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 855625 = 4472^2 + 925^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20854409 is a prime.

Together with 20854411, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20854429) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10427204 + 10427205.

It is an arithmetic number, because the mean of its divisors is an integer number (10427205).

Almost surely, 2^20854409 is an apocalyptic number.

It is an amenable number.

20854409 is a deficient number, since it is larger than the sum of its proper divisors (1).

20854409 is an equidigital number, since it uses as much as digits as its factorization.

20854409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 20854409 is about 4566.6627858864. The cubic root of 20854409 is about 275.2533598941.

The spelling of 20854409 in words is "twenty million, eight hundred fifty-four thousand, four hundred nine".