20436065621 has 2 divisors, whose sum is σ = 20436065622. Its totient is φ = 20436065620.

The previous prime is 20436065599. The next prime is 20436065677. The reversal of 20436065621 is 12656063402.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20046595396 + 389470225 = 141586^2 + 19735^2 .

It is a cyclic number.

It is not a de Polignac number, because 20436065621 - 2³⁰ = 19362323797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20436265621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10218032810 + 10218032811.

It is an arithmetic number, because the mean of its divisors is an integer number (10218032811).

Almost surely, 2^20436065621 is an apocalyptic number.

It is an amenable number.

20436065621 is a deficient number, since it is larger than the sum of its proper divisors (1).

20436065621 is an equidigital number, since it uses as much as digits as its factorization.

20436065621 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 51840, while the sum is 35.

The spelling of 20436065621 in words is "twenty billion, four hundred thirty-six million, sixty-five thousand, six hundred twenty-one".