991351553 has 2 divisors, whose sum is σ = 991351554. Its totient is φ = 991351552.

The previous prime is 991351531. The next prime is 991351577. The reversal of 991351553 is 355153199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 557337664 + 434013889 = 23608^2 + 20833^2 .

It is a cyclic number.

It is not a de Polignac number, because 991351553 - 2¹⁶ = 991286017 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 991351553.

It is not a weakly prime, because it can be changed into another prime (991351513) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495675776 + 495675777.

It is an arithmetic number, because the mean of its divisors is an integer number (495675777).

Almost surely, 2^991351553 is an apocalyptic number.

It is an amenable number.

991351553 is a deficient number, since it is larger than the sum of its proper divisors (1).

991351553 is an equidigital number, since it uses as much as digits as its factorization.

991351553 is an evil number, because the sum of its binary digits is even.

The product of its digits is 91125, while the sum is 41.

The square root of 991351553 is about 31485.7357068244. The cubic root of 991351553 is about 997.1088335455.

The spelling of 991351553 in words is "nine hundred ninety-one million, three hundred fifty-one thousand, five hundred fifty-three".