21532821 has 8 divisors (see below), whose sum is σ = 28732704. Its totient is φ = 14344080.

The previous prime is 21532811. The next prime is 21532837. The reversal of 21532821 is 12823512.

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

It is not a de Polignac number, because 21532821 - 2⁹ = 21532309 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21532791 and 21532800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532801) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4311 + ... + 7851.

It is an arithmetic number, because the mean of its divisors is an integer number (3591588).

Almost surely, 2^21532821 is an apocalyptic number.

It is an amenable number.

21532821 is a deficient number, since it is larger than the sum of its proper divisors (7199883).

21532821 is a wasteful number, since it uses less digits than its factorization.

21532821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5571.

The product of its digits is 960, while the sum is 24.

The square root of 21532821 is about 4640.3470775363. The cubic root of 21532821 is about 278.2063104603.

The spelling of 21532821 in words is "twenty-one million, five hundred thirty-two thousand, eight hundred twenty-one".