16721663 has 8 divisors (see below), whose sum is σ = 19148928. Its totient is φ = 14304024.

The previous prime is 16721657. The next prime is 16721671. The reversal of 16721663 is 36612761.

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

It is not a de Polignac number, because 16721663 - 2⁴ = 16721647 is a prime.

It is a super-2 number, since 2×16721663² = 559228026971138, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16721633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1820 + ... + 6062.

It is an arithmetic number, because the mean of its divisors is an integer number (2393616).

Almost surely, 2^16721663 is an apocalyptic number.

16721663 is a deficient number, since it is larger than the sum of its proper divisors (2427265).

16721663 is an equidigital number, since it uses as much as digits as its factorization.

16721663 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4813.

The product of its digits is 9072, while the sum is 32.

The square root of 16721663 is about 4089.2130049681. The cubic root of 16721663 is about 255.7171303861.

The spelling of 16721663 in words is "sixteen million, seven hundred twenty-one thousand, six hundred sixty-three".