21173459 has 4 divisors (see below), whose sum is σ = 21256104. Its totient is φ = 21090816.

The previous prime is 21173437. The next prime is 21173473. The reversal of 21173459 is 95437112.

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

It is a cyclic number.

It is not a de Polignac number, because 21173459 - 2⁸ = 21173203 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21173419) 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, 40937 + ... + 41450.

It is an arithmetic number, because the mean of its divisors is an integer number (5314026).

Almost surely, 2^21173459 is an apocalyptic number.

21173459 is a deficient number, since it is larger than the sum of its proper divisors (82645).

21173459 is an equidigital number, since it uses as much as digits as its factorization.

21173459 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82644.

The product of its digits is 7560, while the sum is 32.

The square root of 21173459 is about 4601.4627022285. The cubic root of 21173459 is about 276.6499551203.

The spelling of 21173459 in words is "twenty-one million, one hundred seventy-three thousand, four hundred fifty-nine".