16671721 has 8 divisors (see below), whose sum is σ = 19144800. Its totient is φ = 14358240.

The previous prime is 16671701. The next prime is 16671731. The reversal of 16671721 is 12717661.

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 16671721 - 2⁹ = 16671209 is a prime.

It is a super-2 number, since 2×16671721² = 555892562203682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16671701) 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, 39676 + ... + 40093.

It is an arithmetic number, because the mean of its divisors is an integer number (2393100).

Almost surely, 2^16671721 is an apocalyptic number.

16671721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16671721 is a deficient number, since it is larger than the sum of its proper divisors (2473079).

16671721 is a wasteful number, since it uses less digits than its factorization.

16671721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79799.

The product of its digits is 3528, while the sum is 31.

The square root of 16671721 is about 4083.1018845971. The cubic root of 16671721 is about 255.4622960768.

The spelling of 16671721 in words is "sixteen million, six hundred seventy-one thousand, seven hundred twenty-one".