61131990989 has 2 divisors, whose sum is σ = 61131990990. Its totient is φ = 61131990988.

The previous prime is 61131990949. The next prime is 61131991013. The reversal of 61131990989 is 98909913116.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58392306025 + 2739684964 = 241645^2 + 52342^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61131990989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61131990919) 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, 30565995494 + 30565995495.

It is an arithmetic number, because the mean of its divisors is an integer number (30565995495).

Almost surely, 2^61131990989 is an apocalyptic number.

It is an amenable number.

61131990989 is a deficient number, since it is larger than the sum of its proper divisors (1).

61131990989 is an equidigital number, since it uses as much as digits as its factorization.

61131990989 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 944784, while the sum is 56.

The spelling of 61131990989 in words is "sixty-one billion, one hundred thirty-one million, nine hundred ninety thousand, nine hundred eighty-nine".