21436 has 12 divisors (see below), whose sum is σ = 39312. Its totient is φ = 10208.

The previous prime is 21433. The next prime is 21467. The reversal of 21436 is 63412.

It is a d-powerful number, because it can be written as 2⁹ + 1 + 4⁵ + 3⁹ + 6³ .

It is an alternating number because its digits alternate between even and odd.

It is a plaindrome in base 13.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21433) 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, 25 + ... + 208.

It is an arithmetic number, because the mean of its divisors is an integer number (3276).

2²¹⁴³⁶ is an apocalyptic number.

It is an amenable number.

21436 is a deficient number, since it is larger than the sum of its proper divisors (17876).

21436 is a wasteful number, since it uses less digits than its factorization.

21436 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 258 counting only the distinct ones).

The product of its digits is 144, while the sum is 16.

The square root of 21436 is about 146.4103821455. The cubic root of 21436 is about 27.7788704755.

Adding to 21436 its reverse (63412), we get a palindrome (84848).

The spelling of 21436 in words is "twenty-one thousand, four hundred thirty-six".