646863840 has 192 divisors, whose sum is σ = 2587576320. Its totient is φ = 147847680.

The previous prime is 646863829. The next prime is 646863851. The reversal of 646863840 is 48368646.

646863840 is a `hidden beast` number, since 6 + 4 + 6 + 8 + 638 + 4 + 0 = 666.

646863840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (646863829) and next prime (646863851).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 19545 + ... + 40935.

It is an arithmetic number, because the mean of its divisors is an integer number (13476960).

Almost surely, 2^646863840 is an apocalyptic number.

646863840 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 646863840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1293788160).

646863840 is an abundant number, since it is smaller than the sum of its proper divisors (1940712480).

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

646863840 is a wasteful number, since it uses less digits than its factorization.

646863840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21422 (or 21408 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 45.

The square root of 646863840 is about 25433.5180421427. The cubic root of 646863840 is about 864.8436974648.

The spelling of 646863840 in words is "six hundred forty-six million, eight hundred sixty-three thousand, eight hundred forty".