721315181 has 2 divisors, whose sum is σ = 721315182. Its totient is φ = 721315180.

The previous prime is 721315163. The next prime is 721315187. The reversal of 721315181 is 181513127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 691164100 + 30151081 = 26290^2 + 5491^2 .

It is a cyclic number.

It is not a de Polignac number, because 721315181 - 2¹⁸ = 721053037 is a prime.

It is a super-2 number, since 2×721315181² = 1040591180682125522, which contains 22 as substring.

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 (721315187) 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, 360657590 + 360657591.

It is an arithmetic number, because the mean of its divisors is an integer number (360657591).

Almost surely, 2^721315181 is an apocalyptic number.

It is an amenable number.

721315181 is a deficient number, since it is larger than the sum of its proper divisors (1).

721315181 is an equidigital number, since it uses as much as digits as its factorization.

721315181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1680, while the sum is 29.

The square root of 721315181 is about 26857.3114998505. The cubic root of 721315181 is about 896.8263449929.

The spelling of 721315181 in words is "seven hundred twenty-one million, three hundred fifteen thousand, one hundred eighty-one".