1646863920 has 320 divisors, whose sum is σ = 6159605760. Its totient is φ = 402029568.

The previous prime is 1646863853. The next prime is 1646863927. The reversal of 1646863920 is 293686461.

1646863920 is a `hidden beast` number, since 1 + 6 + 4 + 6 + 8 + 639 + 2 + 0 = 666.

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

It is not an unprimeable number, because it can be changed into a prime (1646863927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 6261709 + ... + 6261971.

It is an arithmetic number, because the mean of its divisors is an integer number (19248768).

Almost surely, 2^1646863920 is an apocalyptic number.

1646863920 is a gapful number since it is divisible by the number (10) 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 1646863920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3079802880).

1646863920 is an abundant number, since it is smaller than the sum of its proper divisors (4512741840).

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

1646863920 is a wasteful number, since it uses less digits than its factorization.

1646863920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 521 (or 509 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 45.

The square root of 1646863920 is about 40581.5711869316. The cubic root of 1646863920 is about 1180.9166295335.

The spelling of 1646863920 in words is "one billion, six hundred forty-six million, eight hundred sixty-three thousand, nine hundred twenty".