20518739 has 2 divisors, whose sum is σ = 20518740. Its totient is φ = 20518738.

The previous prime is 20518723. The next prime is 20518777. The reversal of 20518739 is 93781502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20518739 - 2⁴ = 20518723 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20518699 and 20518708.

It is not a weakly prime, because it can be changed into another prime (20518639) 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, 10259369 + 10259370.

It is an arithmetic number, because the mean of its divisors is an integer number (10259370).

Almost surely, 2^20518739 is an apocalyptic number.

20518739 is a deficient number, since it is larger than the sum of its proper divisors (1).

20518739 is an equidigital number, since it uses as much as digits as its factorization.

20518739 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 20518739 is about 4529.7614727489. The cubic root of 20518739 is about 273.7685499964.

The spelling of 20518739 in words is "twenty million, five hundred eighteen thousand, seven hundred thirty-nine".