827121691 has 4 divisors (see below), whose sum is σ = 902314584. Its totient is φ = 751928800.

The previous prime is 827121683. The next prime is 827121697. The reversal of 827121691 is 196121728.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 827121691 - 2³ = 827121683 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 827121691.

It is not an unprimeable number, because it can be changed into a prime (827121697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37596430 + ... + 37596451.

It is an arithmetic number, because the mean of its divisors is an integer number (225578646).

Almost surely, 2^827121691 is an apocalyptic number.

827121691 is a deficient number, since it is larger than the sum of its proper divisors (75192893).

827121691 is a wasteful number, since it uses less digits than its factorization.

827121691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75192892.

The product of its digits is 12096, while the sum is 37.

The square root of 827121691 is about 28759.7234166116. The cubic root of 827121691 is about 938.6920435046.

Adding to 827121691 its sum of digits (37), we get a palindrome (827121728).

The spelling of 827121691 in words is "eight hundred twenty-seven million, one hundred twenty-one thousand, six hundred ninety-one".