721009973 has 2 divisors, whose sum is σ = 721009974. Its totient is φ = 721009972.

The previous prime is 721009963. The next prime is 721010047. The reversal of 721009973 is 379900127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 682358884 + 38651089 = 26122^2 + 6217^2 .

It is a cyclic number.

It is not a de Polignac number, because 721009973 - 2²⁰ = 719961397 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721009903) 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, 360504986 + 360504987.

It is an arithmetic number, because the mean of its divisors is an integer number (360504987).

Almost surely, 2^721009973 is an apocalyptic number.

It is an amenable number.

721009973 is a deficient number, since it is larger than the sum of its proper divisors (1).

721009973 is an equidigital number, since it uses as much as digits as its factorization.

721009973 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23814, while the sum is 38.

The square root of 721009973 is about 26851.6288705173. The cubic root of 721009973 is about 896.6998366383.

The spelling of 721009973 in words is "seven hundred twenty-one million, nine thousand, nine hundred seventy-three".