820165949 has 4 divisors (see below), whose sum is σ = 820638780. Its totient is φ = 819693120.

The previous prime is 820165921. The next prime is 820165967. The reversal of 820165949 is 949561028.

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

It can be written as a sum of positive squares in 2 ways, for example, as 45657049 + 774508900 = 6757^2 + 27830^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-820165949 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820165919) 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, 233804 + ... + 237285.

It is an arithmetic number, because the mean of its divisors is an integer number (205159695).

Almost surely, 2^820165949 is an apocalyptic number.

It is an amenable number.

820165949 is a deficient number, since it is larger than the sum of its proper divisors (472831).

820165949 is a wasteful number, since it uses less digits than its factorization.

820165949 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 472830.

The product of its (nonzero) digits is 155520, while the sum is 44.

The square root of 820165949 is about 28638.5395751948. The cubic root of 820165949 is about 936.0532989623.

The spelling of 820165949 in words is "eight hundred twenty million, one hundred sixty-five thousand, nine hundred forty-nine".