820640117 has 4 divisors (see below), whose sum is σ = 895243776. Its totient is φ = 746036460.

The previous prime is 820640113. The next prime is 820640123. The reversal of 820640117 is 711046028.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 820640117 - 2² = 820640113 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 820640117.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820640113) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 37301813 + ... + 37301834.

It is an arithmetic number, because the mean of its divisors is an integer number (223810944).

Almost surely, 2^820640117 is an apocalyptic number.

It is an amenable number.

820640117 is a deficient number, since it is larger than the sum of its proper divisors (74603659).

820640117 is a wasteful number, since it uses less digits than its factorization.

820640117 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74603658.

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 820640117 is about 28646.8168737820. The cubic root of 820640117 is about 936.2336531186.

The spelling of 820640117 in words is "eight hundred twenty million, six hundred forty thousand, one hundred seventeen".