16551551 has 4 divisors (see below), whose sum is σ = 17085504. Its totient is φ = 16017600.

The previous prime is 16551533. The next prime is 16551583. The reversal of 16551551 is 15515561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 15515561 = 43 ⋅360827.

It is a cyclic number.

It is not a de Polignac number, because 16551551 - 2¹⁸ = 16289407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16551511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 266930 + ... + 266991.

It is an arithmetic number, because the mean of its divisors is an integer number (4271376).

Almost surely, 2^16551551 is an apocalyptic number.

16551551 is a deficient number, since it is larger than the sum of its proper divisors (533953).

16551551 is an equidigital number, since it uses as much as digits as its factorization.

16551551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533952.

The product of its digits is 3750, while the sum is 29.

The square root of 16551551 is about 4068.3597431889. The cubic root of 16551551 is about 254.8470234586.

The spelling of 16551551 in words is "sixteen million, five hundred fifty-one thousand, five hundred fifty-one".