991325789957 has 2 divisors, whose sum is σ = 991325789958. Its totient is φ = 991325789956.

The previous prime is 991325789953. The next prime is 991325790031. The reversal of 991325789957 is 759987523199.

It is an a-pointer prime, because the next prime (991325790031) can be obtained adding 991325789957 to its sum of digits (74).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 970680123361 + 20645666596 = 985231^2 + 143686^2 .

It is a cyclic number.

It is not a de Polignac number, because 991325789957 - 2² = 991325789953 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991325789953) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495662894978 + 495662894979.

It is an arithmetic number, because the mean of its divisors is an integer number (495662894979).

Almost surely, 2^991325789957 is an apocalyptic number.

It is an amenable number.

991325789957 is a deficient number, since it is larger than the sum of its proper divisors (1).

991325789957 is an equidigital number, since it uses as much as digits as its factorization.

991325789957 is an evil number, because the sum of its binary digits is even.

The product of its digits is 385786800, while the sum is 74.

The spelling of 991325789957 in words is "nine hundred ninety-one billion, three hundred twenty-five million, seven hundred eighty-nine thousand, nine hundred fifty-seven".