21533461 has 8 divisors (see below), whose sum is σ = 21873240. Its totient is φ = 21196032.

The previous prime is 21533459. The next prime is 21533471. The reversal of 21533461 is 16433512.

It can be written as a sum of positive squares in 4 ways, for example, as 3129361 + 18404100 = 1769^2 + 4290^2 .

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 21533461 - 2¹ = 21533459 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 (21533431) 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, 27471 + ... + 28243.

It is an arithmetic number, because the mean of its divisors is an integer number (2734155).

Almost surely, 2^21533461 is an apocalyptic number.

It is an amenable number.

21533461 is a deficient number, since it is larger than the sum of its proper divisors (339779).

21533461 is an equidigital number, since it uses as much as digits as its factorization.

21533461 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1175.

The product of its digits is 2160, while the sum is 25.

The square root of 21533461 is about 4640.4160373829. The cubic root of 21533461 is about 278.2090667221.

Adding to 21533461 its reverse (16433512), we get a palindrome (37966973).

The spelling of 21533461 in words is "twenty-one million, five hundred thirty-three thousand, four hundred sixty-one".