21132481 has 2 divisors, whose sum is σ = 21132482. Its totient is φ = 21132480.

The previous prime is 21132383. The next prime is 21132487. The reversal of 21132481 is 18423112.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19000881 + 2131600 = 4359^2 + 1460^2 .

It is a cyclic number.

It is not a de Polignac number, because 21132481 - 2¹³ = 21124289 is a prime.

It is a super-2 number, since 2×21132481² = 893163506430722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21132487) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10566240 + 10566241.

It is an arithmetic number, because the mean of its divisors is an integer number (10566241).

Almost surely, 2^21132481 is an apocalyptic number.

It is an amenable number.

21132481 is a deficient number, since it is larger than the sum of its proper divisors (1).

21132481 is an equidigital number, since it uses as much as digits as its factorization.

21132481 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 22.

The square root of 21132481 is about 4597.0078311876. The cubic root of 21132481 is about 276.4713685995.

Adding to 21132481 its reverse (18423112), we get a palindrome (39555593).

The spelling of 21132481 in words is "twenty-one million, one hundred thirty-two thousand, four hundred eighty-one".