726636721 has 2 divisors, whose sum is σ = 726636722. Its totient is φ = 726636720.

The previous prime is 726636709. The next prime is 726636749. The reversal of 726636721 is 127636627.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 465006096 + 261630625 = 21564^2 + 16175^2 .

It is a cyclic number.

It is not a de Polignac number, because 726636721 - 2⁵ = 726636689 is a prime.

It is not a weakly prime, because it can be changed into another prime (726636221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 363318360 + 363318361.

It is an arithmetic number, because the mean of its divisors is an integer number (363318361).

Almost surely, 2^726636721 is an apocalyptic number.

It is an amenable number.

726636721 is a deficient number, since it is larger than the sum of its proper divisors (1).

726636721 is an equidigital number, since it uses as much as digits as its factorization.

726636721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 40.

The square root of 726636721 is about 26956.2000474844. The cubic root of 726636721 is about 899.0264043720.

The spelling of 726636721 in words is "seven hundred twenty-six million, six hundred thirty-six thousand, seven hundred twenty-one".