720957821 has 2 divisors, whose sum is σ = 720957822. Its totient is φ = 720957820.

The previous prime is 720957803. The next prime is 720957827. The reversal of 720957821 is 128759027.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 573602500 + 147355321 = 23950^2 + 12139^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-720957821 is a prime.

It is a super-2 number, since 2×720957821² = 1039560359322136082, which contains 22 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 (720957827) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360478910 + 360478911.

It is an arithmetic number, because the mean of its divisors is an integer number (360478911).

Almost surely, 2^720957821 is an apocalyptic number.

It is an amenable number.

720957821 is a deficient number, since it is larger than the sum of its proper divisors (1).

720957821 is an equidigital number, since it uses as much as digits as its factorization.

720957821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 70560, while the sum is 41.

The square root of 720957821 is about 26850.6577386849. The cubic root of 720957821 is about 896.6782161249.

The spelling of 720957821 in words is "seven hundred twenty million, nine hundred fifty-seven thousand, eight hundred twenty-one".