21519073 has 4 divisors (see below), whose sum is σ = 22261140. Its totient is φ = 20777008.

The previous prime is 21519067. The next prime is 21519079. The reversal of 21519073 is 37091512.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21519067) and next prime (21519079).

It can be written as a sum of positive squares in 2 ways, for example, as 5702544 + 15816529 = 2388^2 + 3977^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21519073 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21519079) 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, 370990 + ... + 371047.

It is an arithmetic number, because the mean of its divisors is an integer number (5565285).

Almost surely, 2^21519073 is an apocalyptic number.

It is an amenable number.

21519073 is a deficient number, since it is larger than the sum of its proper divisors (742067).

21519073 is an equidigital number, since it uses as much as digits as its factorization.

21519073 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 742066.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 21519073 is about 4638.8654863016. The cubic root of 21519073 is about 278.1470893199.

The spelling of 21519073 in words is "twenty-one million, five hundred nineteen thousand, seventy-three".