20400023221 has 2 divisors, whose sum is σ = 20400023222. Its totient is φ = 20400023220.

The previous prime is 20400023207. The next prime is 20400023251. The reversal of 20400023221 is 12232000402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11127296196 + 9272727025 = 105486^2 + 96295^2 .

It is a cyclic number.

It is not a de Polignac number, because 20400023221 - 2⁷ = 20400023093 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20400023195 and 20400023204.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20400023251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200011610 + 10200011611.

It is an arithmetic number, because the mean of its divisors is an integer number (10200011611).

Almost surely, 2^20400023221 is an apocalyptic number.

It is an amenable number.

20400023221 is a deficient number, since it is larger than the sum of its proper divisors (1).

20400023221 is an equidigital number, since it uses as much as digits as its factorization.

20400023221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 16.

Adding to 20400023221 its reverse (12232000402), we get a palindrome (32632023623).

The spelling of 20400023221 in words is "twenty billion, four hundred million, twenty-three thousand, two hundred twenty-one".