620555681 has 2 divisors, whose sum is σ = 620555682. Its totient is φ = 620555680.

The previous prime is 620555651. The next prime is 620555707. The reversal of 620555681 is 186555026.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 542144656 + 78411025 = 23284^2 + 8855^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-620555681 is a prime.

It is a super-2 number, since 2×620555681² = 770178706442747522, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (620555651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 310277840 + 310277841.

It is an arithmetic number, because the mean of its divisors is an integer number (310277841).

Almost surely, 2^620555681 is an apocalyptic number.

It is an amenable number.

620555681 is a deficient number, since it is larger than the sum of its proper divisors (1).

620555681 is an equidigital number, since it uses as much as digits as its factorization.

620555681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72000, while the sum is 38.

The square root of 620555681 is about 24910.9550399016. The cubic root of 620555681 is about 852.9565697022.

The spelling of 620555681 in words is "six hundred twenty million, five hundred fifty-five thousand, six hundred eighty-one".