646440842 has 16 divisors (see below), whose sum is σ = 984151752. Its totient is φ = 318401280.

The previous prime is 646440811. The next prime is 646440863. The reversal of 646440842 is 248044646.

It can be written as a sum of positive squares in 4 ways, for example, as 617075281 + 29365561 = 24841^2 + 5419^2 .

It is a junction number, because it is equal to n+sod(n) for n = 646440796 and 646440805.

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, 143342 + ... + 147782.

Almost surely, 2^646440842 is an apocalyptic number.

646440842 is a deficient number, since it is larger than the sum of its proper divisors (337710910).

646440842 is a wasteful number, since it uses less digits than its factorization.

646440842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5513.

The product of its (nonzero) digits is 147456, while the sum is 38.

The square root of 646440842 is about 25425.2009234932. The cubic root of 646440842 is about 864.6551431398.

The spelling of 646440842 in words is "six hundred forty-six million, four hundred forty thousand, eight hundred forty-two".