21430173 has 4 divisors (see below), whose sum is σ = 28573568. Its totient is φ = 14286780.

The previous prime is 21430169. The next prime is 21430177. The reversal of 21430173 is 37103412.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21430169) and next prime (21430177).

It is not a de Polignac number, because 21430173 - 2² = 21430169 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3571693 + ... + 3571698.

It is an arithmetic number, because the mean of its divisors is an integer number (7143392).

Almost surely, 2^21430173 is an apocalyptic number.

It is an amenable number.

21430173 is a deficient number, since it is larger than the sum of its proper divisors (7143395).

21430173 is an equidigital number, since it uses as much as digits as its factorization.

21430173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7143394.

The product of its (nonzero) digits is 504, while the sum is 21.

The square root of 21430173 is about 4629.2734851162. The cubic root of 21430173 is about 277.7635318146.

Adding to 21430173 its reverse (37103412), we get a palindrome (58533585).

The spelling of 21430173 in words is "twenty-one million, four hundred thirty thousand, one hundred seventy-three".