7181991961 has 2 divisors, whose sum is σ = 7181991962. Its totient is φ = 7181991960.

The previous prime is 7181991899. The next prime is 7181991979. The reversal of 7181991961 is 1691991817.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 5736547600 + 1445444361 = 75740^2 + 38019^2 .

It is a cyclic number.

It is not a de Polignac number, because 7181991961 - 2¹³ = 7181983769 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 7181991899 and 7181991908.

It is not a weakly prime, because it can be changed into another prime (7181998961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3590995980 + 3590995981.

It is an arithmetic number, because the mean of its divisors is an integer number (3590995981).

Almost surely, 2^7181991961 is an apocalyptic number.

It is an amenable number.

7181991961 is a deficient number, since it is larger than the sum of its proper divisors (1).

7181991961 is an equidigital number, since it uses as much as digits as its factorization.

7181991961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 52.

The square root of 7181991961 is about 84746.6339213541. The cubic root of 7181991961 is about 1929.3675575495.

The spelling of 7181991961 in words is "seven billion, one hundred eighty-one million, nine hundred ninety-one thousand, nine hundred sixty-one".