646615666 has 8 divisors (see below), whose sum is σ = 979340544. Its totient is φ = 320168820.

The previous prime is 646615637. The next prime is 646615667. The reversal of 646615666 is 666516646.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×646615666² = 836223639033247112, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (646615667) 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, 1569250 + ... + 1569661.

It is an arithmetic number, because the mean of its divisors is an integer number (122417568).

Almost surely, 2^646615666 is an apocalyptic number.

646615666 is a deficient number, since it is larger than the sum of its proper divisors (332724878).

646615666 is a wasteful number, since it uses less digits than its factorization.

646615666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3139016.

The product of its digits is 933120, while the sum is 46.

The square root of 646615666 is about 25428.6386973428. The cubic root of 646615666 is about 864.7330821334.

The spelling of 646615666 in words is "six hundred forty-six million, six hundred fifteen thousand, six hundred sixty-six".