21443140 has 12 divisors (see below), whose sum is σ = 45030636. Its totient is φ = 8577248.

The previous prime is 21443131. The next prime is 21443141. The reversal of 21443140 is 4134412.

It can be written as a sum of positive squares in 2 ways, for example, as 8655364 + 12787776 = 2942^2 + 3576^2 .

It is not an unprimeable number, because it can be changed into a prime (21443141) 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, 536059 + ... + 536098.

It is an arithmetic number, because the mean of its divisors is an integer number (3752553).

Almost surely, 2^21443140 is an apocalyptic number.

21443140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21443140 is an abundant number, since it is smaller than the sum of its proper divisors (23587496).

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

21443140 is a wasteful number, since it uses less digits than its factorization.

21443140 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1072166 (or 1072164 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 19.

The square root of 21443140 is about 4630.6738170595. The cubic root of 21443140 is about 277.8195437051.

Adding to 21443140 its reverse (4134412), we get a palindrome (25577552).

The spelling of 21443140 in words is "twenty-one million, four hundred forty-three thousand, one hundred forty".