21505332439 has 2 divisors, whose sum is σ = 21505332440. Its totient is φ = 21505332438.

The previous prime is 21505332379. The next prime is 21505332451. The reversal of 21505332439 is 93423350512.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21505332439 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21505332398 and 21505332407.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21505632439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752666219 + 10752666220.

It is an arithmetic number, because the mean of its divisors is an integer number (10752666220).

Almost surely, 2^21505332439 is an apocalyptic number.

21505332439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21505332439 is an equidigital number, since it uses as much as digits as its factorization.

21505332439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 97200, while the sum is 37.

The spelling of 21505332439 in words is "twenty-one billion, five hundred five million, three hundred thirty-two thousand, four hundred thirty-nine".