51555501661 has 2 divisors, whose sum is σ = 51555501662. Its totient is φ = 51555501660.

The previous prime is 51555501631. The next prime is 51555501671. The reversal of 51555501661 is 16610555515.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 51451848900 + 103652761 = 226830^2 + 10181^2 .

It is a cyclic number.

It is not a de Polignac number, because 51555501661 - 2⁷ = 51555501533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51555501631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25777750830 + 25777750831.

It is an arithmetic number, because the mean of its divisors is an integer number (25777750831).

Almost surely, 2^51555501661 is an apocalyptic number.

It is an amenable number.

51555501661 is a deficient number, since it is larger than the sum of its proper divisors (1).

51555501661 is an equidigital number, since it uses as much as digits as its factorization.

51555501661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 112500, while the sum is 40.

The spelling of 51555501661 in words is "fifty-one billion, five hundred fifty-five million, five hundred one thousand, six hundred sixty-one".