21165891239 has 2 divisors, whose sum is σ = 21165891240. Its totient is φ = 21165891238.

The previous prime is 21165891233. The next prime is 21165891269. The reversal of 21165891239 is 93219856112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21165891239 - 2⁴ = 21165891223 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21165891193 and 21165891202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21165891233) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582945619 + 10582945620.

It is an arithmetic number, because the mean of its divisors is an integer number (10582945620).

Almost surely, 2^21165891239 is an apocalyptic number.

21165891239 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165891239 is an equidigital number, since it uses as much as digits as its factorization.

21165891239 is an evil number, because the sum of its binary digits is even.

The product of its digits is 233280, while the sum is 47.

The spelling of 21165891239 in words is "twenty-one billion, one hundred sixty-five million, eight hundred ninety-one thousand, two hundred thirty-nine".