720731639 has 2 divisors, whose sum is σ = 720731640. Its totient is φ = 720731638.

The previous prime is 720731623. The next prime is 720731681. The reversal of 720731639 is 936137027.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 720731639 - 2⁴ = 720731623 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (720731689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360365819 + 360365820.

It is an arithmetic number, because the mean of its divisors is an integer number (360365820).

Almost surely, 2^720731639 is an apocalyptic number.

720731639 is a deficient number, since it is larger than the sum of its proper divisors (1).

720731639 is an equidigital number, since it uses as much as digits as its factorization.

720731639 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 47628, while the sum is 38.

The square root of 720731639 is about 26846.4455561626. The cubic root of 720731639 is about 896.5844363969.

The spelling of 720731639 in words is "seven hundred twenty million, seven hundred thirty-one thousand, six hundred thirty-nine".