21165019 has 2 divisors, whose sum is σ = 21165020. Its totient is φ = 21165018.

The previous prime is 21165007. The next prime is 21165047. The reversal of 21165019 is 91056112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21165019 - 2²³ = 12776411 is a prime.

It is a super-2 number, since 2×21165019² = 895916058540722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21164984 and 21165002.

It is not a weakly prime, because it can be changed into another prime (21165619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582509 + 10582510.

It is an arithmetic number, because the mean of its divisors is an integer number (10582510).

Almost surely, 2^21165019 is an apocalyptic number.

21165019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165019 is an equidigital number, since it uses as much as digits as its factorization.

21165019 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 540, while the sum is 25.

The square root of 21165019 is about 4600.5455111323. The cubic root of 21165019 is about 276.6131915486.

The spelling of 21165019 in words is "twenty-one million, one hundred sixty-five thousand, nineteen".