20021405 has 4 divisors (see below), whose sum is σ = 24025692. Its totient is φ = 16017120.

The previous prime is 20021399. The next prime is 20021411. The reversal of 20021405 is 50412002.

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

It is an interprime number because it is at equal distance from previous prime (20021399) and next prime (20021411).

It can be written as a sum of positive squares in 2 ways, for example, as 10355524 + 9665881 = 3218^2 + 3109^2 .

It is not a de Polignac number, because 20021405 - 2⁶ = 20021341 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20021405.

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, 2002136 + ... + 2002145.

It is an arithmetic number, because the mean of its divisors is an integer number (6006423).

Almost surely, 2^20021405 is an apocalyptic number.

It is an amenable number.

20021405 is a deficient number, since it is larger than the sum of its proper divisors (4004287).

20021405 is an equidigital number, since it uses as much as digits as its factorization.

20021405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4004286.

The product of its (nonzero) digits is 80, while the sum is 14.

The square root of 20021405 is about 4474.5284667773. The cubic root of 20021405 is about 271.5385639819.

Adding to 20021405 its reverse (50412002), we get a palindrome (70433407).

The spelling of 20021405 in words is "twenty million, twenty-one thousand, four hundred five".