646431840 has 240 divisors, whose sum is σ = 2356421760. Its totient is φ = 166717440.

The previous prime is 646431761. The next prime is 646431899. The reversal of 646431840 is 48134646.

646431840 is a `hidden beast` number, since 6 + 4 + 643 + 1 + 8 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (240).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 646431795 and 646431804.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 400956 + ... + 402564.

It is an arithmetic number, because the mean of its divisors is an integer number (9818424).

Almost surely, 2^646431840 is an apocalyptic number.

646431840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 646431840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1178210880).

646431840 is an abundant number, since it is smaller than the sum of its proper divisors (1709989920).

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

646431840 is a wasteful number, since it uses less digits than its factorization.

646431840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1667 (or 1650 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 36.

The square root of 646431840 is about 25425.0238937941. The cubic root of 646431840 is about 864.6511295415.

The spelling of 646431840 in words is "six hundred forty-six million, four hundred thirty-one thousand, eight hundred forty".