21550530 has 32 divisors (see below), whose sum is σ = 52005888. Its totient is φ = 5715200.

The previous prime is 21550519. The next prime is 21550537. The reversal of 21550530 is 3505512.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21550497 and 21550506.

It is not an unprimeable number, because it can be changed into a prime (21550537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3850 + ... + 7610.

It is an arithmetic number, because the mean of its divisors is an integer number (1625184).

Almost surely, 2^21550530 is an apocalyptic number.

21550530 is an abundant number, since it is smaller than the sum of its proper divisors (30455358).

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

21550530 is a wasteful number, since it uses less digits than its factorization.

21550530 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3962.

The product of its (nonzero) digits is 750, while the sum is 21.

The square root of 21550530 is about 4642.2548400535. The cubic root of 21550530 is about 278.2825569423.

The spelling of 21550530 in words is "twenty-one million, five hundred fifty thousand, five hundred thirty".