21532261 has 4 divisors (see below), whose sum is σ = 22114252. Its totient is φ = 20950272.

The previous prime is 21532249. The next prime is 21532271. The reversal of 21532261 is 16223512.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9036036 + 12496225 = 3006^2 + 3535^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21532261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532201) 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 3 ways as a sum of consecutive naturals, for example, 290940 + ... + 291013.

It is an arithmetic number, because the mean of its divisors is an integer number (5528563).

Almost surely, 2^21532261 is an apocalyptic number.

It is an amenable number.

21532261 is a deficient number, since it is larger than the sum of its proper divisors (581991).

21532261 is an equidigital number, since it uses as much as digits as its factorization.

21532261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 581990.

The product of its digits is 720, while the sum is 22.

The square root of 21532261 is about 4640.2867368300. The cubic root of 21532261 is about 278.2038986864.

Adding to 21532261 its reverse (16223512), we get a palindrome (37755773).

The spelling of 21532261 in words is "twenty-one million, five hundred thirty-two thousand, two hundred sixty-one".