21331646 has 16 divisors (see below), whose sum is σ = 37830240. Its totient is φ = 8826720.

The previous prime is 21331643. The next prime is 21331657. The reversal of 21331646 is 64613312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25865 + ... + 26676.

It is an arithmetic number, because the mean of its divisors is an integer number (2364390).

Almost surely, 2^21331646 is an apocalyptic number.

21331646 is a deficient number, since it is larger than the sum of its proper divisors (16498594).

21331646 is a wasteful number, since it uses less digits than its factorization.

21331646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52579.

The product of its digits is 2592, while the sum is 26.

The square root of 21331646 is about 4618.6194907136. The cubic root of 21331646 is about 277.3371974750.

Adding to 21331646 its reverse (64613312), we get a palindrome (85944958).

The spelling of 21331646 in words is "twenty-one million, three hundred thirty-one thousand, six hundred forty-six".