616665551 has 2 divisors, whose sum is σ = 616665552. Its totient is φ = 616665550.

The previous prime is 616665527. The next prime is 616665557. The reversal of 616665551 is 155566616.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-616665551 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 616665499 and 616665508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (616665557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 308332775 + 308332776.

It is an arithmetic number, because the mean of its divisors is an integer number (308332776).

Almost surely, 2^616665551 is an apocalyptic number.

616665551 is a deficient number, since it is larger than the sum of its proper divisors (1).

616665551 is an equidigital number, since it uses as much as digits as its factorization.

616665551 is an evil number, because the sum of its binary digits is even.

The product of its digits is 162000, while the sum is 41.

The square root of 616665551 is about 24832.7515793156. The cubic root of 616665551 is about 851.1704986046.

It can be divided in two parts, 6166 and 65551, that added together give a palindrome (71717).

The spelling of 616665551 in words is "six hundred sixteen million, six hundred sixty-five thousand, five hundred fifty-one".