21552040 has 16 divisors (see below), whose sum is σ = 48492180. Its totient is φ = 8620800.

The previous prime is 21552031. The next prime is 21552043. The reversal of 21552040 is 4025512.

It can be written as a sum of positive squares in 2 ways, for example, as 19061956 + 2490084 = 4366^2 + 1578^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21551999 and 21552017.

It is not an unprimeable number, because it can be changed into a prime (21552043) 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, 269361 + ... + 269440.

Almost surely, 2^21552040 is an apocalyptic number.

21552040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21552040 is an abundant number, since it is smaller than the sum of its proper divisors (26940140).

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

21552040 is a wasteful number, since it uses less digits than its factorization.

21552040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 538812 (or 538808 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 19.

The square root of 21552040 is about 4642.4174736876. The cubic root of 21552040 is about 278.2890563470.

Adding to 21552040 its reverse (4025512), we get a palindrome (25577552).

The spelling of 21552040 in words is "twenty-one million, five hundred fifty-two thousand, forty".