646668905 has 8 divisors (see below), whose sum is σ = 778452552. Its totient is φ = 515701888.

The previous prime is 646668901. The next prime is 646668931. The reversal of 646668905 is 509866646.

It can be written as a sum of positive squares in 4 ways, for example, as 13039321 + 633629584 = 3611^2 + 25172^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 646668905 - 2² = 646668901 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (646668901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 202412 + ... + 205581.

It is an arithmetic number, because the mean of its divisors is an integer number (97306569).

Almost surely, 2^646668905 is an apocalyptic number.

It is an amenable number.

646668905 is a deficient number, since it is larger than the sum of its proper divisors (131783647).

646668905 is a wasteful number, since it uses less digits than its factorization.

646668905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408315.

The product of its (nonzero) digits is 1866240, while the sum is 50.

The square root of 646668905 is about 25429.6855072964. The cubic root of 646668905 is about 864.7568140366.

The spelling of 646668905 in words is "six hundred forty-six million, six hundred sixty-eight thousand, nine hundred five".