21082819 has 2 divisors, whose sum is σ = 21082820. Its totient is φ = 21082818.

The previous prime is 21082807. The next prime is 21082829. The reversal of 21082819 is 91828012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21082819 - 2¹¹ = 21080771 is a prime.

It is a super-2 number, since 2×21082819² = 888970513973522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21082829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10541409 + 10541410.

It is an arithmetic number, because the mean of its divisors is an integer number (10541410).

Almost surely, 2^21082819 is an apocalyptic number.

21082819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21082819 is an equidigital number, since it uses as much as digits as its factorization.

21082819 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 21082819 is about 4591.6030969586. The cubic root of 21082819 is about 276.2546265682.

The spelling of 21082819 in words is "twenty-one million, eighty-two thousand, eight hundred nineteen".