820004661 has 24 divisors (see below), whose sum is σ = 1413162240. Its totient is φ = 468573336.

The previous prime is 820004651. The next prime is 820004683. The reversal of 820004661 is 166400028.

It is not a de Polignac number, because 820004661 - 2¹⁹ = 819480373 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820004611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 308581 + ... + 311226.

It is an arithmetic number, because the mean of its divisors is an integer number (58881760).

Almost surely, 2^820004661 is an apocalyptic number.

It is an amenable number.

820004661 is a deficient number, since it is larger than the sum of its proper divisors (593157579).

820004661 is a wasteful number, since it uses less digits than its factorization.

820004661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 619830 (or 619817 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 820004661 is about 28635.7235110273. The cubic root of 820004661 is about 935.9919357458.

Adding to 820004661 its reverse (166400028), we get a palindrome (986404689).

The spelling of 820004661 in words is "eight hundred twenty million, four thousand, six hundred sixty-one".