21485173 has 4 divisors (see below), whose sum is σ = 21543148. Its totient is φ = 21427200.

The previous prime is 21485171. The next prime is 21485203. The reversal of 21485173 is 37158412.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18601969 + 2883204 = 4313^2 + 1698^2 .

It is a cyclic number.

It is not a de Polignac number, because 21485173 - 2¹ = 21485171 is a prime.

It is a super-2 number, since 2×21485173² = 923225317679858, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21485171) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28428 + ... + 29173.

It is an arithmetic number, because the mean of its divisors is an integer number (5385787).

Almost surely, 2^21485173 is an apocalyptic number.

It is an amenable number.

21485173 is a deficient number, since it is larger than the sum of its proper divisors (57975).

21485173 is an equidigital number, since it uses as much as digits as its factorization.

21485173 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57974.

The product of its digits is 6720, while the sum is 31.

The square root of 21485173 is about 4635.2101354739. The cubic root of 21485173 is about 278.0009531910. Note that the first 3 decimals are identical.

The spelling of 21485173 in words is "twenty-one million, four hundred eighty-five thousand, one hundred seventy-three".