21411440 has 20 divisors (see below), whose sum is σ = 49781784. Its totient is φ = 8564544.

The previous prime is 21411437. The next prime is 21411457. The reversal of 21411440 is 4411412.

It is a tau number, because it is divible by the number of its divisors (20).

It is a plaindrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 133742 + ... + 133901.

Almost surely, 2^21411440 is an apocalyptic number.

21411440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21411440 is an abundant number, since it is smaller than the sum of its proper divisors (28370344).

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

21411440 is a wasteful number, since it uses less digits than its factorization.

21411440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 267656 (or 267650 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

The square root of 21411440 is about 4627.2497231077. The cubic root of 21411440 is about 277.6825733589.

Adding to 21411440 its reverse (4411412), we get a palindrome (25822852).

The spelling of 21411440 in words is "twenty-one million, four hundred eleven thousand, four hundred forty".