21481408 has 28 divisors (see below), whose sum is σ = 45907960. Its totient is φ = 9914112.

The previous prime is 21481403. The next prime is 21481409. The reversal of 21481408 is 80418412.

It is a super-2 number, since 2×21481408² = 922901779324928, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21481403) 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, 12078 + ... + 13741.

It is an arithmetic number, because the mean of its divisors is an integer number (1639570).

Almost surely, 2^21481408 is an apocalyptic number.

It is an amenable number.

21481408 is an abundant number, since it is smaller than the sum of its proper divisors (24426552).

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

21481408 is a wasteful number, since it uses less digits than its factorization.

21481408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25844 (or 25834 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 28.

The square root of 21481408 is about 4634.8039872253. The cubic root of 21481408 is about 277.9847135462.

The spelling of 21481408 in words is "twenty-one million, four hundred eighty-one thousand, four hundred eight".