726661 has 4 divisors (see below), whose sum is σ = 782572. Its totient is φ = 670752.

The previous prime is 726659. The next prime is 726679. The reversal of 726661 is 166627.

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 245025 + 481636 = 495^2 + 694^2 .

It is a cyclic number.

It is not a de Polignac number, because 726661 - 2¹ = 726659 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 (726601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27936 + ... + 27961.

It is an arithmetic number, because the mean of its divisors is an integer number (195643).

2⁷²⁶⁶⁶¹ is an apocalyptic number.

It is an amenable number.

726661 is a deficient number, since it is larger than the sum of its proper divisors (55911).

726661 is a wasteful number, since it uses less digits than its factorization.

726661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55910.

The product of its digits is 3024, while the sum is 28.

The square root of 726661 is about 852.4441330668. Note that the first 3 decimals coincide. The cubic root of 726661 is about 89.9036417270.

The spelling of 726661 in words is "seven hundred twenty-six thousand, six hundred sixty-one".