20421351539 has 2 divisors, whose sum is σ = 20421351540. Its totient is φ = 20421351538.

The previous prime is 20421351529. The next prime is 20421351557. The reversal of 20421351539 is 93515312402.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20421351539 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 20421351499 and 20421351508.

It is not a weakly prime, because it can be changed into another prime (20421351529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10210675769 + 10210675770.

It is an arithmetic number, because the mean of its divisors is an integer number (10210675770).

Almost surely, 2^20421351539 is an apocalyptic number.

20421351539 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421351539 is an equidigital number, since it uses as much as digits as its factorization.

20421351539 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32400, while the sum is 35.

The spelling of 20421351539 in words is "twenty billion, four hundred twenty-one million, three hundred fifty-one thousand, five hundred thirty-nine".