16551865 has 16 divisors (see below), whose sum is σ = 21822336. Its totient is φ = 11952000.

The previous prime is 16551859. The next prime is 16551877. The reversal of 16551865 is 56815561.

It is not a de Polignac number, because 16551865 - 2⁵ = 16551833 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7309 + ... + 9301.

It is an arithmetic number, because the mean of its divisors is an integer number (1363896).

Almost surely, 2^16551865 is an apocalyptic number.

16551865 is the 3322-nd pentagonal number.

It is an amenable number.

16551865 is a deficient number, since it is larger than the sum of its proper divisors (5270471).

16551865 is a wasteful number, since it uses less digits than its factorization.

16551865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2160.

The product of its digits is 36000, while the sum is 37.

The square root of 16551865 is about 4068.3983334969. The cubic root of 16551865 is about 254.8486350187.

The spelling of 16551865 in words is "sixteen million, five hundred fifty-one thousand, eight hundred sixty-five".