68121640 has 16 divisors (see below), whose sum is σ = 153273780. Its totient is φ = 27248640.

The previous prime is 68121617. The next prime is 68121643. The reversal of 68121640 is 4612186.

It can be written as a sum of positive squares in 2 ways, for example, as 61434244 + 6687396 = 7838^2 + 2586^2 .

It is a junction number, because it is equal to n+sod(n) for n = 68121599 and 68121608.

It is not an unprimeable number, because it can be changed into a prime (68121643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 851481 + ... + 851560.

Almost surely, 2^68121640 is an apocalyptic number.

It is an amenable number.

68121640 is an abundant number, since it is smaller than the sum of its proper divisors (85152140).

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

68121640 is a wasteful number, since it uses less digits than its factorization.

68121640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1703052 (or 1703048 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 68121640 is about 8253.5834641688. The cubic root of 68121640 is about 408.4087439048.

The spelling of 68121640 in words is "sixty-eight million, one hundred twenty-one thousand, six hundred forty".