68640291 has 30 divisors (see below), whose sum is σ = 105553140. Its totient is φ = 44451504.

The previous prime is 68640289. The next prime is 68640317. The reversal of 68640291 is 19204686.

68640291 is a `hidden beast` number, since 6 + 8 + 640 + 2 + 9 + 1 = 666.

It is not a de Polignac number, because 68640291 - 2¹ = 68640289 is a prime.

It is a super-2 number, since 2×68640291² = 9422979097129362, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (68640241) 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 29 ways as a sum of consecutive naturals, for example, 110580 + ... + 111198.

It is an arithmetic number, because the mean of its divisors is an integer number (3518438).

Almost surely, 2^68640291 is an apocalyptic number.

68640291 is a deficient number, since it is larger than the sum of its proper divisors (36912849).

68640291 is an equidigital number, since it uses as much as digits as its factorization.

68640291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 705 (or 659 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 36.

The square root of 68640291 is about 8284.9436328801. The cubic root of 68640291 is about 409.4426116092.

The spelling of 68640291 in words is "sixty-eight million, six hundred forty thousand, two hundred ninety-one".