9941991491 has 2 divisors, whose sum is σ = 9941991492. Its totient is φ = 9941991490.

The previous prime is 9941991481. The next prime is 9941991539. The reversal of 9941991491 is 1941991499.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9941991491 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (9941991481) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4970995745 + 4970995746.

It is an arithmetic number, because the mean of its divisors is an integer number (4970995746).

Almost surely, 2^9941991491 is an apocalyptic number.

9941991491 is a deficient number, since it is larger than the sum of its proper divisors (1).

9941991491 is an equidigital number, since it uses as much as digits as its factorization.

9941991491 is an evil number, because the sum of its binary digits is even.

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

The square root of 9941991491 is about 99709.5356071825. The cubic root of 9941991491 is about 2150.2607573404.

The spelling of 9941991491 in words is "nine billion, nine hundred forty-one million, nine hundred ninety-one thousand, four hundred ninety-one".