61551965789 has 2 divisors, whose sum is σ = 61551965790. Its totient is φ = 61551965788.

The previous prime is 61551965743. The next prime is 61551965837. The reversal of 61551965789 is 98756915516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 39567972889 + 21983992900 = 198917^2 + 148270^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61551965789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61551965719) 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, 30775982894 + 30775982895.

It is an arithmetic number, because the mean of its divisors is an integer number (30775982895).

Almost surely, 2^61551965789 is an apocalyptic number.

It is an amenable number.

61551965789 is a deficient number, since it is larger than the sum of its proper divisors (1).

61551965789 is an equidigital number, since it uses as much as digits as its factorization.

61551965789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412000, while the sum is 62.

The spelling of 61551965789 in words is "sixty-one billion, five hundred fifty-one million, nine hundred sixty-five thousand, seven hundred eighty-nine".