20405923 has 2 divisors, whose sum is σ = 20405924. Its totient is φ = 20405922.

The previous prime is 20405911. The next prime is 20405927. The reversal of 20405923 is 32950402.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20405923 - 2¹⁷ = 20274851 is a prime.

It is not a weakly prime, because it can be changed into another prime (20405927) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202961 + 10202962.

It is an arithmetic number, because the mean of its divisors is an integer number (10202962).

Almost surely, 2^20405923 is an apocalyptic number.

20405923 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405923 is an equidigital number, since it uses as much as digits as its factorization.

20405923 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 20405923 is about 4517.2915557887. The cubic root of 20405923 is about 273.2658834494.

The spelling of 20405923 in words is "twenty million, four hundred five thousand, nine hundred twenty-three".