721261 has 2 divisors, whose sum is σ = 721262. Its totient is φ = 721260.

The previous prime is 721243. The next prime is 721267. The reversal of 721261 is 162127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 367236 + 354025 = 606^2 + 595^2 .

It is a cyclic number.

It is not a de Polignac number, because 721261 - 2⁵ = 721229 is a prime.

It is a Chen prime.

721261 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721267) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360630 + 360631.

It is an arithmetic number, because the mean of its divisors is an integer number (360631).

2⁷²¹²⁶¹ is an apocalyptic number.

It is an amenable number.

721261 is a deficient number, since it is larger than the sum of its proper divisors (1).

721261 is an equidigital number, since it uses as much as digits as its factorization.

721261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 168, while the sum is 19.

The square root of 721261 is about 849.2708637414. The cubic root of 721261 is about 89.6803889638.

Adding to 721261 its reverse (162127), we get a palindrome (883388).

It can be divided in two parts, 72126 and 1, that added together give a palindrome (72127).

The spelling of 721261 in words is "seven hundred twenty-one thousand, two hundred sixty-one".