16720861 has 4 divisors (see below), whose sum is σ = 17076672. Its totient is φ = 16365052.

The previous prime is 16720859. The next prime is 16720871. The reversal of 16720861 is 16802761.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 16720861 - 2¹ = 16720859 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 (16720831) 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, 177835 + ... + 177928.

It is an arithmetic number, because the mean of its divisors is an integer number (4269168).

Almost surely, 2^16720861 is an apocalyptic number.

It is an amenable number.

16720861 is a deficient number, since it is larger than the sum of its proper divisors (355811).

16720861 is an equidigital number, since it uses as much as digits as its factorization.

16720861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355810.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 16720861 is about 4089.1149409133. The cubic root of 16720861 is about 255.7130421081.

The spelling of 16720861 in words is "sixteen million, seven hundred twenty thousand, eight hundred sixty-one".