21600090 has 48 divisors (see below), whose sum is σ = 56710368. Its totient is φ = 5703648.

The previous prime is 21600037. The next prime is 21600091. The reversal of 21600090 is 9000612.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21600091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 8509 + ... + 10751.

It is an arithmetic number, because the mean of its divisors is an integer number (1181466).

Almost surely, 2^21600090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21600090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28355184).

21600090 is an abundant number, since it is smaller than the sum of its proper divisors (35110278).

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

21600090 is a wasteful number, since it uses less digits than its factorization.

21600090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2363 (or 2360 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21600090 is about 4647.5896978972. The cubic root of 21600090 is about 278.4957168153.

The spelling of 21600090 in words is "twenty-one million, six hundred thousand, ninety".