16505521 has 8 divisors (see below), whose sum is σ = 17651304. Its totient is φ = 15379200.

The previous prime is 16505501. The next prime is 16505537. The reversal of 16505521 is 12550561.

It can be written as a sum of positive squares in 4 ways, for example, as 14288400 + 2217121 = 3780^2 + 1489^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 16505521 - 2⁹ = 16505009 is a prime.

It is not an unprimeable number, because it can be changed into a prime (16505501) 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, 3090 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (2206413).

Almost surely, 2^16505521 is an apocalyptic number.

It is an amenable number.

16505521 is a deficient number, since it is larger than the sum of its proper divisors (1145783).

16505521 is a wasteful number, since it uses less digits than its factorization.

16505521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9731.

The product of its (nonzero) digits is 1500, while the sum is 25.

The square root of 16505521 is about 4062.6987336006. The cubic root of 16505521 is about 254.6105602287.

It can be divided in two parts, 16 and 505521, that multiplied together give a square (8088336 = 2844²).

The spelling of 16505521 in words is "sixteen million, five hundred five thousand, five hundred twenty-one".