19430021 has 4 divisors (see below), whose sum is σ = 20924652. Its totient is φ = 17935392.

The previous prime is 19430017. The next prime is 19430039. The reversal of 19430021 is 12003491.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12003491 = 59 ⋅203449.

It can be written as a sum of positive squares in 2 ways, for example, as 8473921 + 10956100 = 2911^2 + 3310^2 .

It is a cyclic number.

It is not a de Polignac number, because 19430021 - 2² = 19430017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19429975 and 19430002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19430041) 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 in 3 ways as a sum of consecutive naturals, for example, 747296 + ... + 747321.

It is an arithmetic number, because the mean of its divisors is an integer number (5231163).

Almost surely, 2^19430021 is an apocalyptic number.

It is an amenable number.

19430021 is a deficient number, since it is larger than the sum of its proper divisors (1494631).

19430021 is a wasteful number, since it uses less digits than its factorization.

19430021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1494630.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 19430021 is about 4407.9497501673. The cubic root of 19430021 is about 268.8382687522.

The spelling of 19430021 in words is "nineteen million, four hundred thirty thousand, twenty-one".