820645013 has 4 divisors (see below), whose sum is σ = 821341068. Its totient is φ = 819948960.

The previous prime is 820645009. The next prime is 820645069. The reversal of 820645013 is 310546028.

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 611177284 + 209467729 = 24722^2 + 14473^2 .

It is a cyclic number.

It is not a de Polignac number, because 820645013 - 2² = 820645009 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 (820645073) 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 3 ways as a sum of consecutive naturals, for example, 346256 + ... + 348617.

It is an arithmetic number, because the mean of its divisors is an integer number (205335267).

Almost surely, 2^820645013 is an apocalyptic number.

It is an amenable number.

820645013 is a deficient number, since it is larger than the sum of its proper divisors (696055).

820645013 is a wasteful number, since it uses less digits than its factorization.

820645013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 696054.

The product of its (nonzero) digits is 5760, while the sum is 29.

The square root of 820645013 is about 28646.9023281750. The cubic root of 820645013 is about 936.2355149948.

The spelling of 820645013 in words is "eight hundred twenty million, six hundred forty-five thousand, thirteen".