20400200021 has 4 divisors (see below), whose sum is σ = 20422399200. Its totient is φ = 20378000844.

The previous prime is 20400200011. The next prime is 20400200033. The reversal of 20400200021 is 12000200402.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12000200402 = 2 ⋅6000100201.

It is a cyclic number.

It is not a de Polignac number, because 20400200021 - 2⁶ = 20400199957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 20400199975 and 20400200011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20400200011) 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, 11098211 + ... + 11100048.

It is an arithmetic number, because the mean of its divisors is an integer number (5105599800).

Almost surely, 2^20400200021 is an apocalyptic number.

It is an amenable number.

20400200021 is a deficient number, since it is larger than the sum of its proper divisors (22199179).

20400200021 is an equidigital number, since it uses as much as digits as its factorization.

20400200021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22199178.

The product of its (nonzero) digits is 32, while the sum is 11.

Adding to 20400200021 its reverse (12000200402), we get a palindrome (32400400423).

The spelling of 20400200021 in words is "twenty billion, four hundred million, two hundred thousand, twenty-one".