991521829 has 2 divisors, whose sum is σ = 991521830. Its totient is φ = 991521828.

The previous prime is 991521799. The next prime is 991521833. The reversal of 991521829 is 928125199.

991521829 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 575280225 + 416241604 = 23985^2 + 20402^2 .

It is an emirp because it is prime and its reverse (928125199) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991521829 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991524829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495760914 + 495760915.

It is an arithmetic number, because the mean of its divisors is an integer number (495760915).

Almost surely, 2^991521829 is an apocalyptic number.

It is an amenable number.

991521829 is a deficient number, since it is larger than the sum of its proper divisors (1).

991521829 is an equidigital number, since it uses as much as digits as its factorization.

991521829 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 46.

The square root of 991521829 is about 31488.4396088469. The cubic root of 991521829 is about 997.1659185702.

The spelling of 991521829 in words is "nine hundred ninety-one million, five hundred twenty-one thousand, eight hundred twenty-nine".