20290405 has 4 divisors (see below), whose sum is σ = 24348492. Its totient is φ = 16232320.

The previous prime is 20290397. The next prime is 20290421. The reversal of 20290405 is 50409202.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 14130081 + 6160324 = 3759^2 + 2482^2 .

It is not a de Polignac number, because 20290405 - 2³ = 20290397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2029036 + ... + 2029045.

It is an arithmetic number, because the mean of its divisors is an integer number (6087123).

Almost surely, 2^20290405 is an apocalyptic number.

It is an amenable number.

20290405 is a deficient number, since it is larger than the sum of its proper divisors (4058087).

20290405 is an equidigital number, since it uses as much as digits as its factorization.

20290405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4058086.

The product of its (nonzero) digits is 720, while the sum is 22.

The square root of 20290405 is about 4504.4872072190. The cubic root of 20290405 is about 272.7492543057.

Adding to 20290405 its reverse (50409202), we get a palindrome (70699607).

It can be divided in two parts, 20 and 290405, that multiplied together give a square (5808100 = 2410²).

The spelling of 20290405 in words is "twenty million, two hundred ninety thousand, four hundred five".