1640646656 has 96 divisors (see below), whose sum is σ = 3768055200. Its totient is φ = 706314240.

The previous prime is 1640646653. The next prime is 1640646731. The reversal of 1640646656 is 6566460461.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is not an unprimeable number, because it can be changed into a prime (1640646653) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 426116 + ... + 429948.

It is an arithmetic number, because the mean of its divisors is an integer number (39250575).

Almost surely, 2^1640646656 is an apocalyptic number.

1640646656 is a gapful number since it is divisible by the number (16) 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 1640646656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1884027600).

1640646656 is an abundant number, since it is smaller than the sum of its proper divisors (2127408544).

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

1640646656 is a wasteful number, since it uses less digits than its factorization.

1640646656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3885 (or 3865 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 44.

The square root of 1640646656 is about 40504.8966916347. The cubic root of 1640646656 is about 1179.4286844598.

The spelling of 1640646656 in words is "one billion, six hundred forty million, six hundred forty-six thousand, six hundred fifty-six".