820666507 has 4 divisors (see below), whose sum is σ = 827128576. Its totient is φ = 814204440.

The previous prime is 820666471. The next prime is 820666529. The reversal of 820666507 is 705666028.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 820666507 - 2¹⁵ = 820633739 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 820666507.

It is not an unprimeable number, because it can be changed into a prime (820666307) 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, 3230844 + ... + 3231097.

It is an arithmetic number, because the mean of its divisors is an integer number (206782144).

Almost surely, 2^820666507 is an apocalyptic number.

820666507 is a deficient number, since it is larger than the sum of its proper divisors (6462069).

820666507 is a wasteful number, since it uses less digits than its factorization.

820666507 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6462068.

The product of its (nonzero) digits is 120960, while the sum is 40.

The square root of 820666507 is about 28647.2774797187. The cubic root of 820666507 is about 936.2436887566.

The spelling of 820666507 in words is "eight hundred twenty million, six hundred sixty-six thousand, five hundred seven".