721328551 has 2 divisors, whose sum is σ = 721328552. Its totient is φ = 721328550.

The previous prime is 721328497. The next prime is 721328563. The reversal of 721328551 is 155823127.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721328551 - 2¹⁷ = 721197479 is a prime.

It is equal to p_37299310 and since 721328551 and 37299310 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is a weakly prime.

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, 360664275 + 360664276.

It is an arithmetic number, because the mean of its divisors is an integer number (360664276).

Almost surely, 2^721328551 is an apocalyptic number.

721328551 is a deficient number, since it is larger than the sum of its proper divisors (1).

721328551 is an equidigital number, since it uses as much as digits as its factorization.

721328551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16800, while the sum is 34.

The square root of 721328551 is about 26857.5604067086. The cubic root of 721328551 is about 896.8318860262.

The spelling of 721328551 in words is "seven hundred twenty-one million, three hundred twenty-eight thousand, five hundred fifty-one".