9972091691 has 2 divisors, whose sum is σ = 9972091692. Its totient is φ = 9972091690.

The previous prime is 9972091643. The next prime is 9972091697. The reversal of 9972091691 is 1961902799.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9972091691 is a prime.

It is a super-2 number, since 2×9972091691² (a number of 21 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (9972091697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4986045845 + 4986045846.

It is an arithmetic number, because the mean of its divisors is an integer number (4986045846).

Almost surely, 2^9972091691 is an apocalyptic number.

9972091691 is a deficient number, since it is larger than the sum of its proper divisors (1).

9972091691 is an equidigital number, since it uses as much as digits as its factorization.

9972091691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 551124, while the sum is 53.

The square root of 9972091691 is about 99860.3609596921. The cubic root of 9972091691 is about 2152.4286016868.

The spelling of 9972091691 in words is "nine billion, nine hundred seventy-two million, ninety-one thousand, six hundred ninety-one".