21132081 has 12 divisors (see below), whose sum is σ = 30567108. Its totient is φ = 14068224.

The previous prime is 21132079. The next prime is 21132103. The reversal of 21132081 is 18023112.

It can be written as a sum of positive squares in 2 ways, for example, as 19713600 + 1418481 = 4440^2 + 1191^2 .

It is not a de Polignac number, because 21132081 - 2¹ = 21132079 is a prime.

It is a super-2 number, since 2×21132081² = 893129694781122, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21132011) 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 11 ways as a sum of consecutive naturals, for example, 8161 + ... + 10433.

It is an arithmetic number, because the mean of its divisors is an integer number (2547259).

Almost surely, 2^21132081 is an apocalyptic number.

It is an amenable number.

21132081 is a deficient number, since it is larger than the sum of its proper divisors (9435027).

21132081 is a wasteful number, since it uses less digits than its factorization.

21132081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3312 (or 3309 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21132081 is about 4596.9643244211. The cubic root of 21132081 is about 276.4696242193.

Adding to 21132081 its reverse (18023112), we get a palindrome (39155193).

The spelling of 21132081 in words is "twenty-one million, one hundred thirty-two thousand, eighty-one".