618997961 has 2 divisors, whose sum is σ = 618997962. Its totient is φ = 618997960.

The previous prime is 618997949. The next prime is 618997991. The reversal of 618997961 is 169799816.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 617820736 + 1177225 = 24856^2 + 1085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-618997961 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 618997897 and 618997906.

It is not a weakly prime, because it can be changed into another prime (618997991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 309498980 + 309498981.

It is an arithmetic number, because the mean of its divisors is an integer number (309498981).

Almost surely, 2^618997961 is an apocalyptic number.

It is an amenable number.

618997961 is a deficient number, since it is larger than the sum of its proper divisors (1).

618997961 is an equidigital number, since it uses as much as digits as its factorization.

618997961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1469664, while the sum is 56.

The square root of 618997961 is about 24879.6696320510. The cubic root of 618997961 is about 852.2422739816.

The spelling of 618997961 in words is "six hundred eighteen million, nine hundred ninety-seven thousand, nine hundred sixty-one".