20405311 has 4 divisors (see below), whose sum is σ = 20511232. Its totient is φ = 20299392.

The previous prime is 20405309. The next prime is 20405317. The reversal of 20405311 is 11350402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20405311 - 2¹ = 20405309 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405317) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52671 + ... + 53056.

It is an arithmetic number, because the mean of its divisors is an integer number (5127808).

Almost surely, 2^20405311 is an apocalyptic number.

20405311 is a deficient number, since it is larger than the sum of its proper divisors (105921).

20405311 is a wasteful number, since it uses less digits than its factorization.

20405311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105920.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 20405311 is about 4517.2238155752. The cubic root of 20405311 is about 273.2631515565.

Adding to 20405311 its reverse (11350402), we get a palindrome (31755713).

The spelling of 20405311 in words is "twenty million, four hundred five thousand, three hundred eleven".