21580019 has 2 divisors, whose sum is σ = 21580020. Its totient is φ = 21580018.

The previous prime is 21580007. The next prime is 21580037. The reversal of 21580019 is 91008512.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21580019 - 2¹⁶ = 21514483 is a prime.

It is a super-2 number, since 2×21580019² = 931394440080722, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21580019.

It is not a weakly prime, because it can be changed into another prime (21580079) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10790009 + 10790010.

It is an arithmetic number, because the mean of its divisors is an integer number (10790010).

Almost surely, 2^21580019 is an apocalyptic number.

21580019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21580019 is an equidigital number, since it uses as much as digits as its factorization.

21580019 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 21580019 is about 4645.4299047559. The cubic root of 21580019 is about 278.4094298329.

The spelling of 21580019 in words is "twenty-one million, five hundred eighty thousand, nineteen".