1636320421 has 2 divisors, whose sum is σ = 1636320422. Its totient is φ = 1636320420.

The previous prime is 1636320419. The next prime is 1636320437. The reversal of 1636320421 is 1240236361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1559144196 + 77176225 = 39486^2 + 8785^2 .

It is a cyclic number.

It is not a de Polignac number, because 1636320421 - 2¹ = 1636320419 is a prime.

Together with 1636320419, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 1636320421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1636320401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 818160210 + 818160211.

It is an arithmetic number, because the mean of its divisors is an integer number (818160211).

Almost surely, 2^1636320421 is an apocalyptic number.

It is an amenable number.

1636320421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1636320421 is an equidigital number, since it uses as much as digits as its factorization.

1636320421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 1636320421 is about 40451.4575880771. The cubic root of 1636320421 is about 1178.3910900968.

Adding to 1636320421 its reverse (1240236361), we get a palindrome (2876556782).

The spelling of 1636320421 in words is "one billion, six hundred thirty-six million, three hundred twenty thousand, four hundred twenty-one".