1681388656 has 40 divisors (see below), whose sum is σ = 3294278240. Its totient is φ = 831285504.

The previous prime is 1681388629. The next prime is 1681388677. The reversal of 1681388656 is 6568831861.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1685950 + ... + 1686946.

It is an arithmetic number, because the mean of its divisors is an integer number (82356956).

Almost surely, 2^1681388656 is an apocalyptic number.

1681388656 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1681388656 is a deficient number, since it is larger than the sum of its proper divisors (1612889584).

1681388656 is a wasteful number, since it uses less digits than its factorization.

1681388656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2081 (or 2075 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 52.

The square root of 1681388656 is about 41004.7394333875. The cubic root of 1681388656 is about 1189.1118425252. Note that the first 3 decimals are identical.

The spelling of 1681388656 in words is "one billion, six hundred eighty-one million, three hundred eighty-eight thousand, six hundred fifty-six".