1640705688 has 24 divisors (see below), whose sum is σ = 4443578100. Its totient is φ = 546901872.

The previous prime is 1640705687. The next prime is 1640705699. The reversal of 1640705688 is 8865070461.

It is a happy number.

1640705688 is a `hidden beast` number, since 16 + 4 + 0 + 70 + 568 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1640705687) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 11393718 + ... + 11393861.

Almost surely, 2^1640705688 is an apocalyptic number.

1640705688 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

1640705688 is an abundant number, since it is smaller than the sum of its proper divisors (2802872412).

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

1640705688 is a wasteful number, since it uses less digits than its factorization.

1640705688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22787591 (or 22787584 counting only the distinct ones).

The product of its (nonzero) digits is 322560, while the sum is 45.

The square root of 1640705688 is about 40505.6253870990. The cubic root of 1640705688 is about 1179.4428299389.

The spelling of 1640705688 in words is "one billion, six hundred forty million, seven hundred five thousand, six hundred eighty-eight".