646646905 has 8 divisors (see below), whose sum is σ = 790617672. Its totient is φ = 507556608.

The previous prime is 646646899. The next prime is 646646927. The reversal of 646646905 is 509646646.

It can be written as a sum of positive squares in 4 ways, for example, as 205520896 + 441126009 = 14336^2 + 21003^2 .

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 646646905 - 2¹⁷ = 646515833 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1219824 + ... + 1220353.

It is an arithmetic number, because the mean of its divisors is an integer number (98827209).

Almost surely, 2^646646905 is an apocalyptic number.

It is an amenable number.

646646905 is a deficient number, since it is larger than the sum of its proper divisors (143970767).

646646905 is a wasteful number, since it uses less digits than its factorization.

646646905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2440235.

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

The square root of 646646905 is about 25429.2529382992. The cubic root of 646646905 is about 864.7470074388.

The spelling of 646646905 in words is "six hundred forty-six million, six hundred forty-six thousand, nine hundred five".