21532553 has 8 divisors (see below), whose sum is σ = 24644160. Its totient is φ = 18429840.

The previous prime is 21532547. The next prime is 21532559. The reversal of 21532553 is 35523512.

It is an interprime number because it is at equal distance from previous prime (21532547) and next prime (21532559).

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

It is a cyclic number.

It is not a de Polignac number, because 21532553 - 2²⁴ = 4755337 is a prime.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (21532559) 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 7 ways as a sum of consecutive naturals, for example, 4223 + ... + 7803.

It is an arithmetic number, because the mean of its divisors is an integer number (3080520).

Almost surely, 2^21532553 is an apocalyptic number.

It is an amenable number.

21532553 is a deficient number, since it is larger than the sum of its proper divisors (3111607).

21532553 is an equidigital number, since it uses as much as digits as its factorization.

21532553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4447.

The product of its digits is 4500, while the sum is 26.

The square root of 21532553 is about 4640.3182002962. The cubic root of 21532553 is about 278.2051562594.

It can be divided in two parts, 215 and 32553, that added together give a 15-th power (32768 = 2¹⁵).

The spelling of 21532553 in words is "twenty-one million, five hundred thirty-two thousand, five hundred fifty-three".