1001561191 has 2 divisors, whose sum is σ = 1001561192. Its totient is φ = 1001561190.

The previous prime is 1001561173. The next prime is 1001561207. The reversal of 1001561191 is 1911651001.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1001561191 - 2⁷ = 1001561063 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1001561101) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 500780595 + 500780596.

It is an arithmetic number, because the mean of its divisors is an integer number (500780596).

Almost surely, 2^1001561191 is an apocalyptic number.

1001561191 is a deficient number, since it is larger than the sum of its proper divisors (1).

1001561191 is an equidigital number, since it uses as much as digits as its factorization.

1001561191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 270, while the sum is 25.

The square root of 1001561191 is about 31647.4515719671. The cubic root of 1001561191 is about 1000.5201264216.

The spelling of 1001561191 in words is "one billion, one million, five hundred sixty-one thousand, one hundred ninety-one".