16821664 has 12 divisors (see below), whose sum is σ = 33117714. Its totient is φ = 8410816.

The previous prime is 16821661. The next prime is 16821677. The reversal of 16821664 is 46612861.

It can be written as a sum of positive squares in only one way, i.e., 16810000 + 11664 = 4100^2 + 108^2 .

It is a hoax number, since the sum of its digits (34) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (16821661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 262807 + ... + 262870.

Almost surely, 2^16821664 is an apocalyptic number.

It is an amenable number.

16821664 is a deficient number, since it is larger than the sum of its proper divisors (16296050).

16821664 is an equidigital number, since it uses as much as digits as its factorization.

16821664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 525687 (or 525679 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 16821664 is about 4101.4221923621. The cubic root of 16821664 is about 256.2258748654.

The spelling of 16821664 in words is "sixteen million, eight hundred twenty-one thousand, six hundred sixty-four".