16991325 has 72 divisors (see below), whose sum is σ = 33874568. Its totient is φ = 8087040.

The previous prime is 16991311. The next prime is 16991327. The reversal of 16991325 is 52319961.

It can be written as a sum of positive squares in 12 ways, for example, as 5560164 + 11431161 = 2358^2 + 3381^2 .

It is not a de Polignac number, because 16991325 - 2⁴ = 16991309 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 16991325.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16991327) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 108147 + ... + 108303.

Almost surely, 2^16991325 is an apocalyptic number.

16991325 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

16991325 is a deficient number, since it is larger than the sum of its proper divisors (16883243).

16991325 is a wasteful number, since it uses less digits than its factorization.

16991325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 223 (or 215 counting only the distinct ones).

The product of its digits is 14580, while the sum is 36.

The square root of 16991325 is about 4122.0534931027. The cubic root of 16991325 is about 257.0844146285.

The spelling of 16991325 in words is "sixteen million, nine hundred ninety-one thousand, three hundred twenty-five".