721163557 has 2 divisors, whose sum is σ = 721163558. Its totient is φ = 721163556.

The previous prime is 721163501. The next prime is 721163567. The reversal of 721163557 is 755361127.

721163557 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 715776516 + 5387041 = 26754^2 + 2321^2 .

It is a cyclic number.

It is not a de Polignac number, because 721163557 - 2¹¹ = 721161509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721163567) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360581778 + 360581779.

It is an arithmetic number, because the mean of its divisors is an integer number (360581779).

Almost surely, 2^721163557 is an apocalyptic number.

It is an amenable number.

721163557 is a deficient number, since it is larger than the sum of its proper divisors (1).

721163557 is an equidigital number, since it uses as much as digits as its factorization.

721163557 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 44100, while the sum is 37.

The square root of 721163557 is about 26854.4885819857. The cubic root of 721163557 is about 896.7635014860.

The spelling of 721163557 in words is "seven hundred twenty-one million, one hundred sixty-three thousand, five hundred fifty-seven".