20456400421 has 2 divisors, whose sum is σ = 20456400422. Its totient is φ = 20456400420.

The previous prime is 20456400389. The next prime is 20456400431. The reversal of 20456400421 is 12400465402.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20013760900 + 442639521 = 141470^2 + 21039^2 .

It is a cyclic number.

It is not a de Polignac number, because 20456400421 - 2⁵ = 20456400389 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20456400421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20456400431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10228200210 + 10228200211.

It is an arithmetic number, because the mean of its divisors is an integer number (10228200211).

Almost surely, 2^20456400421 is an apocalyptic number.

It is an amenable number.

20456400421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20456400421 is an equidigital number, since it uses as much as digits as its factorization.

20456400421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7680, while the sum is 28.

Adding to 20456400421 its reverse (12400465402), we get a palindrome (32856865823).

The spelling of 20456400421 in words is "twenty billion, four hundred fifty-six million, four hundred thousand, four hundred twenty-one".