21130819 has 2 divisors, whose sum is σ = 21130820. Its totient is φ = 21130818.

The previous prime is 21130817. The next prime is 21130829. The reversal of 21130819 is 91803112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21130819 - 2¹ = 21130817 is a prime.

It is a super-2 number, since 2×21130819² = 893023023221522, which contains 22 as substring.

Together with 21130817, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 21130793 and 21130802.

It is not a weakly prime, because it can be changed into another prime (21130817) 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, 10565409 + 10565410.

It is an arithmetic number, because the mean of its divisors is an integer number (10565410).

Almost surely, 2^21130819 is an apocalyptic number.

21130819 is a deficient number, since it is larger than the sum of its proper divisors (1).

21130819 is an equidigital number, since it uses as much as digits as its factorization.

21130819 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 21130819 is about 4596.8270578737. The cubic root of 21130819 is about 276.4641205554.

The spelling of 21130819 in words is "twenty-one million, one hundred thirty thousand, eight hundred nineteen".