16551665 has 16 divisors (see below), whose sum is σ = 21546000. Its totient is φ = 12133632.

The previous prime is 16551653. The next prime is 16551677. The reversal of 16551665 is 56615561.

It is an interprime number because it is at equal distance from previous prime (16551653) and next prime (16551677).

It can be written as a sum of positive squares in 8 ways, for example, as 6105841 + 10445824 = 2471^2 + 3232^2 .

It is a cyclic number.

It is not a de Polignac number, because 16551665 - 2¹⁰ = 16550641 is a prime.

It is a super-2 number, since 2×16551665² = 547915228544450, which contains 22 as substring.

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, 8831 + ... + 10539.

It is an arithmetic number, because the mean of its divisors is an integer number (1346625).

Almost surely, 2^16551665 is an apocalyptic number.

It is an amenable number.

16551665 is a deficient number, since it is larger than the sum of its proper divisors (4994335).

16551665 is a wasteful number, since it uses less digits than its factorization.

16551665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1876.

The product of its digits is 27000, while the sum is 35.

The square root of 16551665 is about 4068.3737537252. The cubic root of 16551665 is about 254.8476085497.

The spelling of 16551665 in words is "sixteen million, five hundred fifty-one thousand, six hundred sixty-five".