21271440 has 80 divisors (see below), whose sum is σ = 66388608. Its totient is φ = 5634048.

The previous prime is 21271429. The next prime is 21271451. The reversal of 21271440 is 4417212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21271429) and next prime (21271451).

It is a tau number, because it is divible by the number of its divisors (80).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62952 + ... + 63288.

Almost surely, 2^21271440 is an apocalyptic number.

21271440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21271440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33194304).

21271440 is an abundant number, since it is smaller than the sum of its proper divisors (45117168).

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

21271440 is a wasteful number, since it uses less digits than its factorization.

21271440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 616 (or 610 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 21.

The square root of 21271440 is about 4612.0971368782. The cubic root of 21271440 is about 277.0760346819.

Adding to 21271440 its reverse (4417212), we get a palindrome (25688652).

The spelling of 21271440 in words is "twenty-one million, two hundred seventy-one thousand, four hundred forty".