646401918 has 16 divisors (see below), whose sum is σ = 1295464320. Its totient is φ = 215023896.

The previous prime is 646401911. The next prime is 646401947. The reversal of 646401918 is 819104646.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646401911) 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, 107688 + ... + 113531.

It is an arithmetic number, because the mean of its divisors is an integer number (80966520).

Almost surely, 2^646401918 is an apocalyptic number.

646401918 is an abundant number, since it is smaller than the sum of its proper divisors (649062402).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

646401918 is a wasteful number, since it uses less digits than its factorization.

646401918 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221711.

The product of its (nonzero) digits is 41472, while the sum is 39.

The square root of 646401918 is about 25424.4354509594. The cubic root of 646401918 is about 864.6377883616.

The spelling of 646401918 in words is "six hundred forty-six million, four hundred one thousand, nine hundred eighteen".