1640656 has 30 divisors (see below), whose sum is σ = 3311606. Its totient is φ = 787200.

The previous prime is 1640641. The next prime is 1640657. The reversal of 1640656 is 6560461.

1640656 is nontrivially palindromic in base 3.

It can be written as a sum of positive squares in 3 ways, for example, as 341056 + 1299600 = 584^2 + 1140^2 .

It is a super-2 number, since 2×1640656² = 5383504220672, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 26866 + ... + 26926.

2^1640656 is an apocalyptic number.

1640656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1640656 is an abundant number, since it is smaller than the sum of its proper divisors (1670950).

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

1640656 is an equidigital number, since it uses as much as digits as its factorization.

1640656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151 (or 104 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 1640656 is about 1280.8809468487. The cubic root of 1640656 is about 117.9430923528.

The spelling of 1640656 in words is "one million, six hundred forty thousand, six hundred fifty-six".