21531066 has 16 divisors (see below), whose sum is σ = 45328800. Its totient is φ = 6799248.

The previous prime is 21531049. The next prime is 21531071. The reversal of 21531066 is 66013512.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 94321 + ... + 94548.

It is an arithmetic number, because the mean of its divisors is an integer number (2833050).

Almost surely, 2^21531066 is an apocalyptic number.

21531066 is an abundant number, since it is smaller than the sum of its proper divisors (23797734).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21531066 is a wasteful number, since it uses less digits than its factorization.

21531066 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188893.

The product of its (nonzero) digits is 1080, while the sum is 24.

The square root of 21531066 is about 4640.1579714488. The cubic root of 21531066 is about 278.1987519934.

Adding to 21531066 its reverse (66013512), we get a palindrome (87544578).

The spelling of 21531066 in words is "twenty-one million, five hundred thirty-one thousand, sixty-six".