720705991 has 2 divisors, whose sum is σ = 720705992. Its totient is φ = 720705990.

The previous prime is 720705961. The next prime is 720706013. The reversal of 720705991 is 199507027.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 720705991 - 2⁵ = 720705959 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (720705961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360352995 + 360352996.

It is an arithmetic number, because the mean of its divisors is an integer number (360352996).

Almost surely, 2^720705991 is an apocalyptic number.

720705991 is a deficient number, since it is larger than the sum of its proper divisors (1).

720705991 is an equidigital number, since it uses as much as digits as its factorization.

720705991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 39690, while the sum is 40.

The square root of 720705991 is about 26845.9678722895. The cubic root of 720705991 is about 896.5738009680.

The spelling of 720705991 in words is "seven hundred twenty million, seven hundred five thousand, nine hundred ninety-one".