68640640 has 32 divisors (see below), whose sum is σ = 164095560. Its totient is φ = 27456000.

The previous prime is 68640631. The next prime is 68640647. The reversal of 68640640 is 4604686.

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 68640596 and 68640605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68640647) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 52986 + ... + 54265.

Almost surely, 2^68640640 is an apocalyptic number.

It is an amenable number.

68640640 is an abundant number, since it is smaller than the sum of its proper divisors (95454920).

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

68640640 is a wasteful number, since it uses less digits than its factorization.

68640640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107270 (or 107258 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 34.

The square root of 68640640 is about 8284.9646951571. The cubic root of 68640640 is about 409.4433055419.

The spelling of 68640640 in words is "sixty-eight million, six hundred forty thousand, six hundred forty".