21021020539 has 2 divisors, whose sum is σ = 21021020540. Its totient is φ = 21021020538.

The previous prime is 21021020513. The next prime is 21021020543. The reversal of 21021020539 is 93502012012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21021020539 - 2¹⁷ = 21020889467 is a prime.

It is not a weakly prime, because it can be changed into another prime (21021020599) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510510269 + 10510510270.

It is an arithmetic number, because the mean of its divisors is an integer number (10510510270).

Almost surely, 2^21021020539 is an apocalyptic number.

21021020539 is a deficient number, since it is larger than the sum of its proper divisors (1).

21021020539 is an equidigital number, since it uses as much as digits as its factorization.

21021020539 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1080, while the sum is 25.

The spelling of 21021020539 in words is "twenty-one billion, twenty-one million, twenty thousand, five hundred thirty-nine".