991385501 has 2 divisors, whose sum is σ = 991385502. Its totient is φ = 991385500.

The previous prime is 991385489. The next prime is 991385513. The reversal of 991385501 is 105583199.

It is a balanced prime because it is at equal distance from previous prime (991385489) and next prime (991385513).

It can be written as a sum of positive squares in only one way, i.e., 989165401 + 2220100 = 31451^2 + 1490^2 .

It is an emirp because it is prime and its reverse (105583199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991385501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991385581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495692750 + 495692751.

It is an arithmetic number, because the mean of its divisors is an integer number (495692751).

Almost surely, 2^991385501 is an apocalyptic number.

It is an amenable number.

991385501 is a deficient number, since it is larger than the sum of its proper divisors (1).

991385501 is an equidigital number, since it uses as much as digits as its factorization.

991385501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48600, while the sum is 41.

The square root of 991385501 is about 31486.2748034759. The cubic root of 991385501 is about 997.1202151333.

The spelling of 991385501 in words is "nine hundred ninety-one million, three hundred eighty-five thousand, five hundred one".