20405771 has 2 divisors, whose sum is σ = 20405772. Its totient is φ = 20405770.

The previous prime is 20405767. The next prime is 20405783. The reversal of 20405771 is 17750402.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20405771 - 2² = 20405767 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20405771.

It is not a weakly prime, because it can be changed into another prime (20404771) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202885 + 10202886.

It is an arithmetic number, because the mean of its divisors is an integer number (10202886).

Almost surely, 2^20405771 is an apocalyptic number.

20405771 is a deficient number, since it is larger than the sum of its proper divisors (1).

20405771 is an equidigital number, since it uses as much as digits as its factorization.

20405771 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 20405771 is about 4517.2747315168. The cubic root of 20405771 is about 273.2652049452.

The spelling of 20405771 in words is "twenty million, four hundred five thousand, seven hundred seventy-one".