16387561 has 4 divisors (see below), whose sum is σ = 16916224. Its totient is φ = 15858900.

The previous prime is 16387549. The next prime is 16387583. The reversal of 16387561 is 16578361.

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.

It is a cyclic number.

It is not a de Polignac number, because 16387561 - 2⁷ = 16387433 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16387561.

It is not an unprimeable number, because it can be changed into a prime (16387361) 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, 264285 + ... + 264346.

It is an arithmetic number, because the mean of its divisors is an integer number (4229056).

Almost surely, 2^16387561 is an apocalyptic number.

It is an amenable number.

16387561 is a deficient number, since it is larger than the sum of its proper divisors (528663).

16387561 is an equidigital number, since it uses as much as digits as its factorization.

16387561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 528662.

The product of its digits is 30240, while the sum is 37.

The square root of 16387561 is about 4048.1552588803. The cubic root of 16387561 is about 254.0025678125.

The spelling of 16387561 in words is "sixteen million, three hundred eighty-seven thousand, five hundred sixty-one".