21471440 has 40 divisors (see below), whose sum is σ = 50139648. Its totient is φ = 8551040.

The previous prime is 21471409. The next prime is 21471449. The reversal of 21471440 is 4417412.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (40).

It is a super-2 number, since 2×21471440² = 922045471347200, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471449) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24449 + ... + 25311.

Almost surely, 2^21471440 is an apocalyptic number.

21471440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21471440 is an abundant number, since it is smaller than the sum of its proper divisors (28668208).

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

21471440 is a wasteful number, since it uses less digits than its factorization.

21471440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1187 (or 1181 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 23.

The square root of 21471440 is about 4633.7285203171. The cubic root of 21471440 is about 277.9417092215.

Adding to 21471440 its reverse (4417412), we get a palindrome (25888852).

The spelling of 21471440 in words is "twenty-one million, four hundred seventy-one thousand, four hundred forty".