21532471 has 4 divisors (see below), whose sum is σ = 22275000. Its totient is φ = 20789944.

The previous prime is 21532417. The next prime is 21532499. The reversal of 21532471 is 17423512.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21532471 - 2¹⁷ = 21401399 is a prime.

It is a super-3 number, since 3×21532471³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532271) 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 3 ways as a sum of consecutive naturals, for example, 371221 + ... + 371278.

It is an arithmetic number, because the mean of its divisors is an integer number (5568750).

Almost surely, 2^21532471 is an apocalyptic number.

21532471 is a deficient number, since it is larger than the sum of its proper divisors (742529).

21532471 is an equidigital number, since it uses as much as digits as its factorization.

21532471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 742528.

The product of its digits is 1680, while the sum is 25.

The square root of 21532471 is about 4640.3093646868. The cubic root of 21532471 is about 278.2048031065.

Adding to 21532471 its reverse (17423512), we get a palindrome (38955983).

It can be divided in two parts, 2153 and 2471, that added together give a square (4624 = 68²).

The spelling of 21532471 in words is "twenty-one million, five hundred thirty-two thousand, four hundred seventy-one".