21481236 has 36 divisors (see below), whose sum is σ = 62057632. Its totient is φ = 6137424.

The previous prime is 21481231. The next prime is 21481259. The reversal of 21481236 is 63218412.

It is a tau number, because it is divible by the number of its divisors (36).

It is a super-2 number, since 2×21481236² = 922887000175392, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481231) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 42370 + ... + 42873.

Almost surely, 2^21481236 is an apocalyptic number.

It is an amenable number.

21481236 is an abundant number, since it is smaller than the sum of its proper divisors (40576396).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21481236 is a wasteful number, since it uses less digits than its factorization.

21481236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85260 (or 85255 counting only the distinct ones).

The product of its digits is 2304, while the sum is 27.

The square root of 21481236 is about 4634.7854319267. The cubic root of 21481236 is about 277.9839716101.

Adding to 21481236 its reverse (63218412), we get a palindrome (84699648).

The spelling of 21481236 in words is "twenty-one million, four hundred eighty-one thousand, two hundred thirty-six".