20436021 has 6 divisors (see below), whose sum is σ = 29518710. Its totient is φ = 13624008.

The previous prime is 20436019. The next prime is 20436041. The reversal of 20436021 is 12063402.

It is a happy number.

20436021 is a `hidden beast` number, since 20 + 43 + 602 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 19236996 + 1199025 = 4386^2 + 1095^2 .

It is not a de Polignac number, because 20436021 - 2¹ = 20436019 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20435985 and 20436003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20436041) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1135326 + ... + 1135343.

It is an arithmetic number, because the mean of its divisors is an integer number (4919785).

Almost surely, 2^20436021 is an apocalyptic number.

It is an amenable number.

20436021 is a deficient number, since it is larger than the sum of its proper divisors (9082689).

20436021 is a wasteful number, since it uses less digits than its factorization.

20436021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2270675 (or 2270672 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 18.

The square root of 20436021 is about 4520.6217492730. The cubic root of 20436021 is about 273.4001698873.

Adding to 20436021 its reverse (12063402), we get a palindrome (32499423).

The spelling of 20436021 in words is "twenty million, four hundred thirty-six thousand, twenty-one".