820640101 has 4 divisors (see below), whose sum is σ = 820705600. Its totient is φ = 820574604.

The previous prime is 820640087. The next prime is 820640113. The reversal of 820640101 is 101046028.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 820640101 - 2¹¹ = 820638053 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820640141) 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, 7431 + ... + 41188.

It is an arithmetic number, because the mean of its divisors is an integer number (205176400).

Almost surely, 2^820640101 is an apocalyptic number.

It is an amenable number.

820640101 is a deficient number, since it is larger than the sum of its proper divisors (65499).

820640101 is a wasteful number, since it uses less digits than its factorization.

820640101 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65498.

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 820640101 is about 28646.8165945188. The cubic root of 820640101 is about 936.2336470341.

Adding to 820640101 its reverse (101046028), we get a palindrome (921686129).

The spelling of 820640101 in words is "eight hundred twenty million, six hundred forty thousand, one hundred one".