16509987 has 20 divisors (see below), whose sum is σ = 26561920. Its totient is φ = 10159344.

The previous prime is 16509971. The next prime is 16509989. The reversal of 16509987 is 78990561.

It is not a de Polignac number, because 16509987 - 2⁴ = 16509971 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (16509989) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6787 + ... + 8892.

It is an arithmetic number, because the mean of its divisors is an integer number (1328096).

Almost surely, 2^16509987 is an apocalyptic number.

16509987 is a deficient number, since it is larger than the sum of its proper divisors (10051933).

16509987 is a wasteful number, since it uses less digits than its factorization.

16509987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15704 (or 15695 counting only the distinct ones).

The product of its (nonzero) digits is 136080, while the sum is 45.

The square root of 16509987 is about 4063.2483310770. The cubic root of 16509987 is about 254.6335220045.

The spelling of 16509987 in words is "sixteen million, five hundred nine thousand, nine hundred eighty-seven".