646640404658 has 4 divisors (see below), whose sum is σ = 969960606990. Its totient is φ = 323320202328.

The previous prime is 646640404649. The next prime is 646640404673. The reversal of 646640404658 is 856404046646.

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., 598947522889 + 47692881769 = 773917^2 + 218387^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 161660101163 + ... + 161660101166.

Almost surely, 2^646640404658 is an apocalyptic number.

646640404658 is a deficient number, since it is larger than the sum of its proper divisors (323320202332).

646640404658 is a wasteful number, since it uses less digits than its factorization.

646640404658 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 323320202331.

The product of its (nonzero) digits is 13271040, while the sum is 53.

It can be divided in two parts, 6 and 46640404658, that added together give a palindrome (46640404664).

The spelling of 646640404658 in words is "six hundred forty-six billion, six hundred forty million, four hundred four thousand, six hundred fifty-eight".