16209681 has 8 divisors (see below), whose sum is σ = 21631680. Its totient is φ = 10797072.

The previous prime is 16209643. The next prime is 16209691. The reversal of 16209681 is 18690261.

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

It is not a de Polignac number, because 16209681 - 2⁶ = 16209617 is a prime.

It is a super-2 number, since 2×16209681² = 525507516243522, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (16209691) 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, 4756 + ... + 7418.

It is an arithmetic number, because the mean of its divisors is an integer number (2703960).

Almost surely, 2^16209681 is an apocalyptic number.

It is an amenable number.

16209681 is a deficient number, since it is larger than the sum of its proper divisors (5421999).

16209681 is a wasteful number, since it uses less digits than its factorization.

16209681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4695.

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 16209681 is about 4026.1248117762. The cubic root of 16209681 is about 253.0801924650.

The spelling of 16209681 in words is "sixteen million, two hundred nine thousand, six hundred eighty-one".