21550288 has 20 divisors (see below), whose sum is σ = 44210340. Its totient is φ = 10141184.

The previous prime is 21550283. The next prime is 21550289. The reversal of 21550288 is 88205512.

It can be written as a sum of positive squares in 2 ways, for example, as 17909824 + 3640464 = 4232^2 + 1908^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21550283) 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, 39343 + ... + 39886.

It is an arithmetic number, because the mean of its divisors is an integer number (2210517).

Almost surely, 2^21550288 is an apocalyptic number.

It is an amenable number.

21550288 is an abundant number, since it is smaller than the sum of its proper divisors (22660052).

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

21550288 is a wasteful number, since it uses less digits than its factorization.

21550288 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79254 (or 79248 counting only the distinct ones).

The product of its (nonzero) digits is 6400, while the sum is 31.

The square root of 21550288 is about 4642.2287750605. The cubic root of 21550288 is about 278.2815152877.

The spelling of 21550288 in words is "twenty-one million, five hundred fifty thousand, two hundred eighty-eight".