26721665 has 4 divisors (see below), whose sum is σ = 32066004. Its totient is φ = 21377328.

The previous prime is 26721649. The next prime is 26721679. The reversal of 26721665 is 56612762.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15904144 + 10817521 = 3988^2 + 3289^2 .

It is a cyclic number.

It is not a de Polignac number, because 26721665 - 2⁴ = 26721649 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2672162 + ... + 2672171.

It is an arithmetic number, because the mean of its divisors is an integer number (8016501).

Almost surely, 2^26721665 is an apocalyptic number.

It is an amenable number.

26721665 is a deficient number, since it is larger than the sum of its proper divisors (5344339).

26721665 is an equidigital number, since it uses as much as digits as its factorization.

26721665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5344338.

The product of its digits is 30240, while the sum is 35.

The square root of 26721665 is about 5169.3002427795. The cubic root of 26721665 is about 298.9655668897.

The spelling of 26721665 in words is "twenty-six million, seven hundred twenty-one thousand, six hundred sixty-five".