20405071 has 4 divisors (see below), whose sum is σ = 21292272. Its totient is φ = 19517872.

The previous prime is 20405059. The next prime is 20405081. The reversal of 20405071 is 17050402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 17050402 = 2 ⋅8525201.

It is a cyclic number.

It is not a de Polignac number, because 20405071 - 2⁵ = 20405039 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 (20405041) 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, 443566 + ... + 443611.

It is an arithmetic number, because the mean of its divisors is an integer number (5323068).

Almost surely, 2^20405071 is an apocalyptic number.

20405071 is a deficient number, since it is larger than the sum of its proper divisors (887201).

20405071 is an equidigital number, since it uses as much as digits as its factorization.

20405071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 887200.

The product of its (nonzero) digits is 280, while the sum is 19.

The square root of 20405071 is about 4517.1972505083. The cubic root of 20405071 is about 273.2620802110.

Adding to 20405071 its reverse (17050402), we get a palindrome (37455473).

The spelling of 20405071 in words is "twenty million, four hundred five thousand, seventy-one".