821165099 has 4 divisors (see below), whose sum is σ = 821567136. Its totient is φ = 820763064.

The previous prime is 821165089. The next prime is 821165117. The reversal of 821165099 is 990561128.

It is a happy number.

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 821165099 - 2⁴ = 821165083 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (821165039) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 197939 + ... + 202044.

It is an arithmetic number, because the mean of its divisors is an integer number (205391784).

Almost surely, 2^821165099 is an apocalyptic number.

821165099 is a deficient number, since it is larger than the sum of its proper divisors (402037).

821165099 is a wasteful number, since it uses less digits than its factorization.

821165099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 402036.

The product of its (nonzero) digits is 38880, while the sum is 41.

The square root of 821165099 is about 28655.9784163794. The cubic root of 821165099 is about 936.4332538261.

The spelling of 821165099 in words is "eight hundred twenty-one million, one hundred sixty-five thousand, ninety-nine".