620742781 has 2 divisors, whose sum is σ = 620742782. Its totient is φ = 620742780.

The previous prime is 620742779. The next prime is 620742809. The reversal of 620742781 is 187247026.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 452625625 + 168117156 = 21275^2 + 12966^2 .

It is a cyclic number.

It is not a de Polignac number, because 620742781 - 2¹ = 620742779 is a prime.

It is a super-2 number, since 2×620742781² = 770643200327227922, which contains 22 as substring.

Together with 620742779, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 620742781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (620742701) 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, 310371390 + 310371391.

It is an arithmetic number, because the mean of its divisors is an integer number (310371391).

Almost surely, 2^620742781 is an apocalyptic number.

It is an amenable number.

620742781 is a deficient number, since it is larger than the sum of its proper divisors (1).

620742781 is an equidigital number, since it uses as much as digits as its factorization.

620742781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 37632, while the sum is 37.

The square root of 620742781 is about 24914.7101327710. The cubic root of 620742781 is about 853.0422843517.

The spelling of 620742781 in words is "six hundred twenty million, seven hundred forty-two thousand, seven hundred eighty-one".