16601521 has 4 divisors (see below), whose sum is σ = 16649712. Its totient is φ = 16553332.

The previous prime is 16601509. The next prime is 16601539. The reversal of 16601521 is 12510661.

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: 12510661 = 397 ⋅31513.

It is a cyclic number.

It is not a de Polignac number, because 16601521 - 2¹⁵ = 16568753 is a prime.

It is a super-2 number, since 2×16601521² = 551220999026882, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 16601492 and 16601501.

It is not an unprimeable number, because it can be changed into a prime (16601551) 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, 23575 + ... + 24268.

It is an arithmetic number, because the mean of its divisors is an integer number (4162428).

Almost surely, 2^16601521 is an apocalyptic number.

It is an amenable number.

16601521 is a deficient number, since it is larger than the sum of its proper divisors (48191).

16601521 is an equidigital number, since it uses as much as digits as its factorization.

16601521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48190.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 16601521 is about 4074.4964106009. The cubic root of 16601521 is about 255.1032313035.

The spelling of 16601521 in words is "sixteen million, six hundred one thousand, five hundred twenty-one".