21550521 has 8 divisors (see below), whose sum is σ = 28770304. Its totient is φ = 14348880.

The previous prime is 21550519. The next prime is 21550537. The reversal of 21550521 is 12505512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21550521 - 2¹ = 21550519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21550561) 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 7 ways as a sum of consecutive naturals, for example, 1465 + ... + 6726.

It is an arithmetic number, because the mean of its divisors is an integer number (3596288).

Almost surely, 2^21550521 is an apocalyptic number.

It is an amenable number.

21550521 is a deficient number, since it is larger than the sum of its proper divisors (7219783).

21550521 is an equidigital number, since it uses as much as digits as its factorization.

21550521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9071.

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 21550521 is about 4642.2538706969. The cubic root of 21550521 is about 278.2825182033.

The spelling of 21550521 in words is "twenty-one million, five hundred fifty thousand, five hundred twenty-one".