21031019 has 2 divisors, whose sum is σ = 21031020. Its totient is φ = 21031018.

The previous prime is 21031009. The next prime is 21031027. The reversal of 21031019 is 91013012.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21031019 - 2²⁴ = 4253803 is a prime.

It is a super-2 number, since 2×21031019² = 884607520356722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21030988 and 21031006.

It is not a weakly prime, because it can be changed into another prime (21031009) 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, 10515509 + 10515510.

It is an arithmetic number, because the mean of its divisors is an integer number (10515510).

Almost surely, 2^21031019 is an apocalyptic number.

21031019 is a deficient number, since it is larger than the sum of its proper divisors (1).

21031019 is an equidigital number, since it uses as much as digits as its factorization.

21031019 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54, while the sum is 17.

The square root of 21031019 is about 4585.9588964578. The cubic root of 21031019 is about 276.0281906023.

The spelling of 21031019 in words is "twenty-one million, thirty-one thousand, nineteen".