68640840 has 48 divisors (see below), whose sum is σ = 223083900. Its totient is φ = 18304128.

The previous prime is 68640839. The next prime is 68640881. The reversal of 68640840 is 4804686.

68640840 is a `hidden beast` number, since 6 + 8 + 640 + 8 + 4 + 0 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 64931364 + 3709476 = 8058^2 + 1926^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 68640795 and 68640804.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 94975 + ... + 95694.

Almost surely, 2^68640840 is an apocalyptic number.

68640840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

68640840 is an abundant number, since it is smaller than the sum of its proper divisors (154443060).

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

68640840 is a wasteful number, since it uses less digits than its factorization.

68640840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190686 (or 190679 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The square root of 68640840 is about 8284.9767652058. The cubic root of 68640840 is about 409.4437032101.

The spelling of 68640840 in words is "sixty-eight million, six hundred forty thousand, eight hundred forty".