20406439 has 2 divisors, whose sum is σ = 20406440. Its totient is φ = 20406438.

The previous prime is 20406403. The next prime is 20406461. The reversal of 20406439 is 93460402.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20406439 - 2⁷ = 20406311 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20406539) 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, 10203219 + 10203220.

It is an arithmetic number, because the mean of its divisors is an integer number (10203220).

Almost surely, 2^20406439 is an apocalyptic number.

20406439 is a deficient number, since it is larger than the sum of its proper divisors (1).

20406439 is an equidigital number, since it uses as much as digits as its factorization.

20406439 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 20406439 is about 4517.3486692971. The cubic root of 20406439 is about 273.2681867677.

The spelling of 20406439 in words is "twenty million, four hundred six thousand, four hundred thirty-nine".