820664626 has 4 divisors (see below), whose sum is σ = 1230996942. Its totient is φ = 410332312.

The previous prime is 820664599. The next prime is 820664627. The reversal of 820664626 is 626466028.

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

It can be written as a sum of positive squares in only one way, i.e., 745235401 + 75429225 = 27299^2 + 8685^2 .

It is not an unprimeable number, because it can be changed into a prime (820664627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 205166155 + ... + 205166158.

Almost surely, 2^820664626 is an apocalyptic number.

820664626 is a deficient number, since it is larger than the sum of its proper divisors (410332316).

820664626 is a wasteful number, since it uses less digits than its factorization.

820664626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410332315.

The product of its (nonzero) digits is 165888, while the sum is 40.

The square root of 820664626 is about 28647.2446493550. The cubic root of 820664626 is about 936.2429734536.

The spelling of 820664626 in words is "eight hundred twenty million, six hundred sixty-four thousand, six hundred twenty-six".