19000021 has 4 divisors (see below), whose sum is σ = 19009612. Its totient is φ = 18990432.

The previous prime is 19000013. The next prime is 19000027. The reversal of 19000021 is 12000091.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 7535025 + 11464996 = 2745^2 + 3386^2 .

It is a cyclic number.

It is not a de Polignac number, because 19000021 - 2³ = 19000013 is a prime.

It is a super-2 number, since 2×19000021² = 722001596000882, which contains 22 as substring.

It is a Duffinian number.

19000021 is a modest number, since divided by 21 gives 19 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 18999965 and 19000010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19000027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 600 + ... + 6193.

It is an arithmetic number, because the mean of its divisors is an integer number (4752403).

Almost surely, 2^19000021 is an apocalyptic number.

It is an amenable number.

19000021 is a deficient number, since it is larger than the sum of its proper divisors (9591).

19000021 is an equidigital number, since it uses as much as digits as its factorization.

19000021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9590.

The product of its (nonzero) digits is 18, while the sum is 13.

The square root of 19000021 is about 4358.9013524052. The cubic root of 19000021 is about 266.8402631817.

The spelling of 19000021 in words is "nineteen million, twenty-one", and thus it is an aban number and an uban number.