21479 has 4 divisors (see below), whose sum is σ = 21984. Its totient is φ = 20976.

The previous prime is 21467. The next prime is 21481. The reversal of 21479 is 97412.

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 21479 - 2¹² = 17383 is a prime.

It is a super-2 number, since 2×21479² = 922694882, which contains 22 as substring.

It is a Duffinian number.

Its product of digits (504) is a multiple of the sum of its prime divisors (504).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21479.

It is not an unprimeable number, because it can be changed into a prime (21419) 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, 182 + ... + 275.

It is an arithmetic number, because the mean of its divisors is an integer number (5496).

2²¹⁴⁷⁹ is an apocalyptic number.

21479 is a deficient number, since it is larger than the sum of its proper divisors (505).

21479 is an equidigital number, since it uses as much as digits as its factorization.

21479 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504.

The product of its digits is 504, while the sum is 23.

The square root of 21479 is about 146.5571560859. The cubic root of 21479 is about 27.7974326080.

The spelling of 21479 in words is "twenty-one thousand, four hundred seventy-nine".