21475 has 6 divisors (see below), whose sum is σ = 26660. Its totient is φ = 17160.

The previous prime is 21467. The next prime is 21481. The reversal of 21475 is 57412.

It is not a de Polignac number, because 21475 - 2³ = 21467 is a prime.

It is a super-2 number, since 2×21475² = 922351250, which contains 22 as substring.

21475 is a lucky number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 405 + ... + 454.

2²¹⁴⁷⁵ is an apocalyptic number.

21475 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21475 is a deficient number, since it is larger than the sum of its proper divisors (5185).

21475 is an equidigital number, since it uses as much as digits as its factorization.

21475 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 869 (or 864 counting only the distinct ones).

The product of its digits is 280, while the sum is 19.

The square root of 21475 is about 146.5435088975. The cubic root of 21475 is about 27.7957069436.

Adding to 21475 its reverse (57412), we get a palindrome (78887).

Subtracting 21475 from its reverse (57412), we obtain a cube (35937 = 33³).

It can be divided in two parts, 214 and 75, that added together give a square (289 = 17²).

The spelling of 21475 in words is "twenty-one thousand, four hundred seventy-five".