646646906 has 4 divisors (see below), whose sum is σ = 969970362. Its totient is φ = 323323452.

The previous prime is 646646899. The next prime is 646646927. The reversal of 646646906 is 609646646.

It is a happy number.

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., 491021281 + 155625625 = 22159^2 + 12475^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161661725 + ... + 161661728.

Almost surely, 2^646646906 is an apocalyptic number.

646646906 is a deficient number, since it is larger than the sum of its proper divisors (323323456).

646646906 is a wasteful number, since it uses less digits than its factorization.

646646906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323323455.

The product of its (nonzero) digits is 1119744, while the sum is 47.

The square root of 646646906 is about 25429.2529579616. The cubic root of 646646906 is about 864.7470078845.

The spelling of 646646906 in words is "six hundred forty-six million, six hundred forty-six thousand, nine hundred six".