16002561 has 4 divisors (see below), whose sum is σ = 21336752. Its totient is φ = 10668372.

The previous prime is 16002551. The next prime is 16002563. The reversal of 16002561 is 16520061.

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 an emirpimes, since its reverse is a distinct semiprime: 16520061 = 3 ⋅5506687.

It is not a de Polignac number, because 16002561 - 2⁵ = 16002529 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16002563) 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, 2667091 + ... + 2667096.

It is an arithmetic number, because the mean of its divisors is an integer number (5334188).

Almost surely, 2^16002561 is an apocalyptic number.

It is an amenable number.

16002561 is a deficient number, since it is larger than the sum of its proper divisors (5334191).

16002561 is an equidigital number, since it uses as much as digits as its factorization.

16002561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5334190.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 16002561 is about 4000.3201121910. The cubic root of 16002561 is about 251.9976536693.

The spelling of 16002561 in words is "sixteen million, two thousand, five hundred sixty-one".