21273 has 8 divisors (see below), whose sum is σ = 32448. Its totient is φ = 12144.

The previous prime is 21269. The next prime is 21277. The reversal of 21273 is 37212.

It is an interprime number because it is at equal distance from previous prime (21269) and next prime (21277).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21273 - 2² = 21269 is a prime.

It is a Smith number, since the sum of its digits (15) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21277) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 486 + ... + 527.

It is an arithmetic number, because the mean of its divisors is an integer number (4056).

2²¹²⁷³ is an apocalyptic number.

It is an amenable number.

21273 is a deficient number, since it is larger than the sum of its proper divisors (11175).

21273 is a wasteful number, since it uses less digits than its factorization.

21273 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1023.

The product of its digits is 84, while the sum is 15.

The square root of 21273 is about 145.8526653853. The cubic root of 21273 is about 27.7082807896.

Adding to 21273 its reverse (37212), we get a palindrome (58485).

It can be divided in two parts, 2 and 1273, that added together give a triangular number (1275 = T₅₀).

The spelling of 21273 in words is "twenty-one thousand, two hundred seventy-three", and thus it is an iban number.