646686646 has 4 divisors (see below), whose sum is σ = 970029972. Its totient is φ = 323343322.

The previous prime is 646686637. The next prime is 646686659.

646686646 is nontrivially palindromic in base 10.

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

It is a super-2 number, since 2×646686646² = 836407236229458632, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 646686593 and 646686602.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161671660 + ... + 161671663.

It is an arithmetic number, because the mean of its divisors is an integer number (242507493).

Almost surely, 2^646686646 is an apocalyptic number.

646686646 is a deficient number, since it is larger than the sum of its proper divisors (323343326).

646686646 is a wasteful number, since it uses less digits than its factorization.

646686646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 323343325.

The product of its digits is 5971968, while the sum is 52.

The square root of 646686646 is about 25430.0343295089. The cubic root of 646686646 is about 864.7647220043.

The spelling of 646686646 in words is "six hundred forty-six million, six hundred eighty-six thousand, six hundred forty-six".