20211409 has 4 divisors (see below), whose sum is σ = 20220516. Its totient is φ = 20202304.

The previous prime is 20211407. The next prime is 20211461. The reversal of 20211409 is 90411202.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7049025 + 13162384 = 2655^2 + 3628^2 .

It is a cyclic number.

It is not a de Polignac number, because 20211409 - 2¹ = 20211407 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20211407) 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, 1197 + ... + 6469.

It is an arithmetic number, because the mean of its divisors is an integer number (5055129).

Almost surely, 2^20211409 is an apocalyptic number.

It is an amenable number.

20211409 is a deficient number, since it is larger than the sum of its proper divisors (9107).

20211409 is an equidigital number, since it uses as much as digits as its factorization.

20211409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9106.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 20211409 is about 4495.7100662743. The cubic root of 20211409 is about 272.3948319023.

It can be divided in two parts, 202 and 11409, that added together give a palindrome (11611).

The spelling of 20211409 in words is "twenty million, two hundred eleven thousand, four hundred nine".