2991097561 has 2 divisors, whose sum is σ = 2991097562. Its totient is φ = 2991097560.

The previous prime is 2991097519. The next prime is 2991097579. The reversal of 2991097561 is 1657901992.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2818017225 + 173080336 = 53085^2 + 13156^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2991097561 is a prime.

It is not a weakly prime, because it can be changed into another prime (2991092561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1495548780 + 1495548781.

It is an arithmetic number, because the mean of its divisors is an integer number (1495548781).

Almost surely, 2^2991097561 is an apocalyptic number.

It is an amenable number.

2991097561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2991097561 is an equidigital number, since it uses as much as digits as its factorization.

2991097561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 306180, while the sum is 49.

The square root of 2991097561 is about 54690.9275931575. The cubic root of 2991097561 is about 1440.8215414009.

The spelling of 2991097561 in words is "two billion, nine hundred ninety-one million, ninety-seven thousand, five hundred sixty-one".