720705221 has 2 divisors, whose sum is σ = 720705222. Its totient is φ = 720705220.

The previous prime is 720705151. The next prime is 720705281. The reversal of 720705221 is 122507027.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 495285025 + 225420196 = 22255^2 + 15014^2 .

It is a cyclic number.

It is not a de Polignac number, because 720705221 - 2¹⁰ = 720704197 is a prime.

It is a super-3 number, since 3×720705221³ (a number of 28 digits) contains 333 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (720705281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360352610 + 360352611.

It is an arithmetic number, because the mean of its divisors is an integer number (360352611).

Almost surely, 2^720705221 is an apocalyptic number.

It is an amenable number.

720705221 is a deficient number, since it is larger than the sum of its proper divisors (1).

720705221 is an equidigital number, since it uses as much as digits as its factorization.

720705221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 720705221 is about 26845.9535312121. The cubic root of 720705221 is about 896.5734816690.

The spelling of 720705221 in words is "seven hundred twenty million, seven hundred five thousand, two hundred twenty-one".