21621066 has 32 divisors (see below), whose sum is σ = 45109440. Its totient is φ = 6900096.

The previous prime is 21621053. The next prime is 21621073. The reversal of 21621066 is 66012612.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23385 + ... + 24291.

It is an arithmetic number, because the mean of its divisors is an integer number (1409670).

Almost surely, 2^21621066 is an apocalyptic number.

21621066 is an abundant number, since it is smaller than the sum of its proper divisors (23488374).

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

21621066 is a wasteful number, since it uses less digits than its factorization.

21621066 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1078.

The product of its (nonzero) digits is 864, while the sum is 24.

The square root of 21621066 is about 4649.8458038950. The cubic root of 21621066 is about 278.5858373687.

Adding to 21621066 its reverse (66012612), we get a palindrome (87633678).

The spelling of 21621066 in words is "twenty-one million, six hundred twenty-one thousand, sixty-six".