1688234778 has 128 divisors (see below), whose sum is σ = 4112640000. Its totient is φ = 511505280.

The previous prime is 1688234773. The next prime is 1688234789. The reversal of 1688234778 is 8774328861.

It is a happy number.

1688234778 is a `hidden beast` number, since 168 + 8 + 2 + 3 + 477 + 8 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1688234771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 2818123 + ... + 2818721.

It is an arithmetic number, because the mean of its divisors is an integer number (32130000).

Almost surely, 2^1688234778 is an apocalyptic number.

1688234778 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1688234778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2056320000).

1688234778 is an abundant number, since it is smaller than the sum of its proper divisors (2424405222).

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

1688234778 is a wasteful number, since it uses less digits than its factorization.

1688234778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 737 (or 731 counting only the distinct ones).

The product of its digits is 3612672, while the sum is 54.

The square root of 1688234778 is about 41088.1342725610. The cubic root of 1688234778 is about 1190.7235620310.

The spelling of 1688234778 in words is "one billion, six hundred eighty-eight million, two hundred thirty-four thousand, seven hundred seventy-eight".