9991437997 has 2 divisors, whose sum is σ = 9991437998. Its totient is φ = 9991437996.

The previous prime is 9991437979. The next prime is 9991438007. The reversal of 9991437997 is 7997341999.

Together with previous prime (9991437979) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8728417476 + 1263020521 = 93426^2 + 35539^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-9991437997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (9991437397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995718998 + 4995718999.

It is an arithmetic number, because the mean of its divisors is an integer number (4995718999).

Almost surely, 2^9991437997 is an apocalyptic number.

It is an amenable number.

9991437997 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991437997 is an equidigital number, since it uses as much as digits as its factorization.

9991437997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 34720812, while the sum is 67.

The square root of 9991437997 is about 99957.1808175881. The cubic root of 9991437997 is about 2153.8196385867.

The spelling of 9991437997 in words is "nine billion, nine hundred ninety-one million, four hundred thirty-seven thousand, nine hundred ninety-seven".