2618621561 has 2 divisors, whose sum is σ = 2618621562. Its totient is φ = 2618621560.

The previous prime is 2618621549. The next prime is 2618621563. The reversal of 2618621561 is 1651268162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2151197161 + 467424400 = 46381^2 + 21620^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2618621561 is a prime.

Together with 2618621563, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2618621563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1309310780 + 1309310781.

It is an arithmetic number, because the mean of its divisors is an integer number (1309310781).

Almost surely, 2^2618621561 is an apocalyptic number.

It is an amenable number.

2618621561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2618621561 is an equidigital number, since it uses as much as digits as its factorization.

2618621561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34560, while the sum is 38.

The square root of 2618621561 is about 51172.4687796084. The cubic root of 2618621561 is about 1378.3438721765.

The spelling of 2618621561 in words is "two billion, six hundred eighteen million, six hundred twenty-one thousand, five hundred sixty-one".