16691641 has 4 divisors (see below), whose sum is σ = 16699984. Its totient is φ = 16683300.

The previous prime is 16691621. The next prime is 16691651. The reversal of 16691641 is 14619661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 16691641 - 2¹¹ = 16689593 is a prime.

It is a super-2 number, since 2×16691641² = 557221758545762, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16691597 and 16691606.

It is not an unprimeable number, because it can be changed into a prime (16691621) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 826 + ... + 5836.

It is an arithmetic number, because the mean of its divisors is an integer number (4174996).

Almost surely, 2^16691641 is an apocalyptic number.

It is an amenable number.

16691641 is a deficient number, since it is larger than the sum of its proper divisors (8343).

16691641 is an equidigital number, since it uses as much as digits as its factorization.

16691641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8342.

The product of its digits is 7776, while the sum is 34.

The square root of 16691641 is about 4085.5404783211. The cubic root of 16691641 is about 255.5640009041.

The spelling of 16691641 in words is "sixteen million, six hundred ninety-one thousand, six hundred forty-one".