16821649 has 8 divisors (see below), whose sum is σ = 18150272. Its totient is φ = 15498000.

The previous prime is 16821611. The next prime is 16821661. The reversal of 16821649 is 94612861.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 16821649 - 2¹⁵ = 16788881 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16821689) 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, 8902 + ... + 10624.

It is an arithmetic number, because the mean of its divisors is an integer number (2268784).

Almost surely, 2^16821649 is an apocalyptic number.

It is an amenable number.

16821649 is a deficient number, since it is larger than the sum of its proper divisors (1328623).

16821649 is a wasteful number, since it uses less digits than its factorization.

16821649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2487.

The product of its digits is 20736, while the sum is 37.

The square root of 16821649 is about 4101.4203637277. The cubic root of 16821649 is about 256.2257987059.

The spelling of 16821649 in words is "sixteen million, eight hundred twenty-one thousand, six hundred forty-nine".