646401556 has 12 divisors (see below), whose sum is σ = 1137977568. Its totient is φ = 321265112.

The previous prime is 646401541. The next prime is 646401559. The reversal of 646401556 is 655104646.

It is a super-2 number, since 2×646401556² = 835669943198442272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (646401559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 483166 + ... + 484501.

It is an arithmetic number, because the mean of its divisors is an integer number (94831464).

Almost surely, 2^646401556 is an apocalyptic number.

It is an amenable number.

646401556 is a deficient number, since it is larger than the sum of its proper divisors (491576012).

646401556 is a wasteful number, since it uses less digits than its factorization.

646401556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 967838 (or 967836 counting only the distinct ones).

The product of its (nonzero) digits is 86400, while the sum is 37.

The square root of 646401556 is about 25424.4283318229. The cubic root of 646401556 is about 864.6376269559.

The spelling of 646401556 in words is "six hundred forty-six million, four hundred one thousand, five hundred fifty-six".