21002215439 has 2 divisors, whose sum is σ = 21002215440. Its totient is φ = 21002215438.

The previous prime is 21002215387. The next prime is 21002215441. The reversal of 21002215439 is 93451220012.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002215439 is a prime.

Together with 21002215441, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21002235439) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10501107719 + 10501107720.

It is an arithmetic number, because the mean of its divisors is an integer number (10501107720).

Almost surely, 2^21002215439 is an apocalyptic number.

21002215439 is a deficient number, since it is larger than the sum of its proper divisors (1).

21002215439 is an equidigital number, since it uses as much as digits as its factorization.

21002215439 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 29.

The spelling of 21002215439 in words is "twenty-one billion, two million, two hundred fifteen thousand, four hundred thirty-nine".