16561403 has 6 divisors (see below), whose sum is σ = 17313324. Its totient is φ = 15840836.

The previous prime is 16561399. The next prime is 16561411. The reversal of 16561403 is 30416561.

It is not a de Polignac number, because 16561403 - 2² = 16561399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16561423) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15125 + ... + 16182.

It is an arithmetic number, because the mean of its divisors is an integer number (2885554).

Almost surely, 2^16561403 is an apocalyptic number.

16561403 is a deficient number, since it is larger than the sum of its proper divisors (751921).

16561403 is an equidigital number, since it uses as much as digits as its factorization.

16561403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31353 (or 31330 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 16561403 is about 4069.5703704445. The cubic root of 16561403 is about 254.8975777315.

Adding to 16561403 its reverse (30416561), we get a palindrome (46977964).

The spelling of 16561403 in words is "sixteen million, five hundred sixty-one thousand, four hundred three".