16561925 has 6 divisors (see below), whose sum is σ = 20536818. Its totient is φ = 13249520.

The previous prime is 16561913. The next prime is 16561969. The reversal of 16561925 is 52916561.

It can be written as a sum of positive squares in 3 ways, for example, as 2775556 + 13786369 = 1666^2 + 3713^2 .

It is not a de Polignac number, because 16561925 - 2⁶ = 16561861 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 331214 + ... + 331263.

It is an arithmetic number, because the mean of its divisors is an integer number (3422803).

Almost surely, 2^16561925 is an apocalyptic number.

It is an amenable number.

16561925 is a deficient number, since it is larger than the sum of its proper divisors (3974893).

16561925 is an equidigital number, since it uses as much as digits as its factorization.

16561925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 662487 (or 662482 counting only the distinct ones).

The product of its digits is 16200, while the sum is 35.

The square root of 16561925 is about 4069.6345044733. The cubic root of 16561925 is about 254.9002557482.

The spelling of 16561925 in words is "sixteen million, five hundred sixty-one thousand, nine hundred twenty-five".