16720261 has 4 divisors (see below), whose sum is σ = 16729900. Its totient is φ = 16710624.

The previous prime is 16720243. The next prime is 16720279. The reversal of 16720261 is 16202761.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 16202761 = 397 ⋅40813.

It is an interprime number because it is at equal distance from previous prime (16720243) and next prime (16720279).

It can be written as a sum of positive squares in 2 ways, for example, as 7756225 + 8964036 = 2785^2 + 2994^2 .

It is a cyclic number.

It is not a de Polignac number, because 16720261 - 2⁹ = 16719749 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 (16723261) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1416 + ... + 5953.

It is an arithmetic number, because the mean of its divisors is an integer number (4182475).

Almost surely, 2^16720261 is an apocalyptic number.

It is an amenable number.

16720261 is a deficient number, since it is larger than the sum of its proper divisors (9639).

16720261 is an equidigital number, since it uses as much as digits as its factorization.

16720261 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9638.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 16720261 is about 4089.0415747458. The cubic root of 16720261 is about 255.7099834606.

The spelling of 16720261 in words is "sixteen million, seven hundred twenty thousand, two hundred sixty-one".