21254440 has 32 divisors (see below), whose sum is σ = 48305160. Its totient is φ = 8416000.

The previous prime is 21254417. The next prime is 21254447. The reversal of 21254440 is 4445212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 21215236 + 39204 = 4606^2 + 198^2 .

It is not an unprimeable number, because it can be changed into a prime (21254447) 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, 1410 + ... + 6670.

Almost surely, 2^21254440 is an apocalyptic number.

21254440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21254440 is an abundant number, since it is smaller than the sum of its proper divisors (27050720).

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

21254440 is a wasteful number, since it uses less digits than its factorization.

21254440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5373 (or 5369 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

The square root of 21254440 is about 4610.2537891097. The cubic root of 21254440 is about 277.0022025395.

Adding to 21254440 its reverse (4445212), we get a palindrome (25699652).

The spelling of 21254440 in words is "twenty-one million, two hundred fifty-four thousand, four hundred forty".