16516621 has 6 divisors (see below), whose sum is σ = 18154766. Its totient is φ = 15015000.

The previous prime is 16516613. The next prime is 16516657. The reversal of 16516621 is 12661561.

It can be written as a sum of positive squares in only one way, i.e., 11628100 + 4888521 = 3410^2 + 2211^2 .

It is not a de Polignac number, because 16516621 - 2³ = 16516613 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 16516621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16516021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 68130 + ... + 68371.

Almost surely, 2^16516621 is an apocalyptic number.

16516621 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

16516621 is a deficient number, since it is larger than the sum of its proper divisors (1638145).

16516621 is a wasteful number, since it uses less digits than its factorization.

16516621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136523 (or 136512 counting only the distinct ones).

The product of its digits is 2160, while the sum is 28.

The square root of 16516621 is about 4064.0645910221. The cubic root of 16516621 is about 254.6676228305.

The spelling of 16516621 in words is "sixteen million, five hundred sixteen thousand, six hundred twenty-one".