72703721 has 2 divisors, whose sum is σ = 72703722. Its totient is φ = 72703720.

The previous prime is 72703703. The next prime is 72703723. The reversal of 72703721 is 12730727.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 61387225 + 11316496 = 7835^2 + 3364^2 .

It is an emirp because it is prime and its reverse (12730727) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 72703721 - 2²² = 68509417 is a prime.

Together with 72703723, it forms a pair of twin primes.

It is a Chen prime.

It is equal to p_4267640 and since 72703721 and 4267640 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (72703723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36351860 + 36351861.

It is an arithmetic number, because the mean of its divisors is an integer number (36351861).

Almost surely, 2^72703721 is an apocalyptic number.

It is an amenable number.

72703721 is a deficient number, since it is larger than the sum of its proper divisors (1).

72703721 is an equidigital number, since it uses as much as digits as its factorization.

72703721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4116, while the sum is 29.

The square root of 72703721 is about 8526.6477000050. The cubic root of 72703721 is about 417.3677418209.

The spelling of 72703721 in words is "seventy-two million, seven hundred three thousand, seven hundred twenty-one".