20405911 has 2 divisors, whose sum is σ = 20405912. Its totient is φ = 20405910.

The previous prime is 20405893. The next prime is 20405923. The reversal of 20405911 is 11950402.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20405911 - 2⁷ = 20405783 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20405941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202955 + 10202956.

It is an arithmetic number, because the mean of its divisors is an integer number (10202956).

Almost surely, 2^20405911 is an apocalyptic number.

20405911 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405911 is an equidigital number, since it uses as much as digits as its factorization.

20405911 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 20405911 is about 4517.2902275590. The cubic root of 20405911 is about 273.2658298834.

It can be divided in two parts, 20405 and 911, that added together give a square (21316 = 146²).

The spelling of 20405911 in words is "twenty million, four hundred five thousand, nine hundred eleven".