765820821 has 32 divisors (see below), whose sum is σ = 1089648000. Its totient is φ = 477066240.

The previous prime is 765820817. The next prime is 765820823. The reversal of 765820821 is 128028567.

It is not a de Polignac number, because 765820821 - 2² = 765820817 is a prime.

It is a super-2 number, since 2×765820821² = 1172963059754228082, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 765820821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (765820823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2194155 + ... + 2194503.

It is an arithmetic number, because the mean of its divisors is an integer number (34051500).

Almost surely, 2^765820821 is an apocalyptic number.

It is an amenable number.

765820821 is a deficient number, since it is larger than the sum of its proper divisors (323827179).

765820821 is a wasteful number, since it uses less digits than its factorization.

765820821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 789.

The product of its (nonzero) digits is 53760, while the sum is 39.

The square root of 765820821 is about 27673.4678166651. The cubic root of 765820821 is about 914.9044147515.

The spelling of 765820821 in words is "seven hundred sixty-five million, eight hundred twenty thousand, eight hundred twenty-one".