68690921 has 8 divisors (see below), whose sum is σ = 74041800. Its totient is φ = 63349632.

The previous prime is 68690893. The next prime is 68690929. The reversal of 68690921 is 12909686.

68690921 = 5860² + 5861².

It can be written as a sum of positive squares in 4 ways, for example, as 215296 + 68475625 = 464^2 + 8275^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 68690921 - 2¹⁰ = 68689897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68690929) 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 7 ways as a sum of consecutive naturals, for example, 21005 + ... + 24053.

It is an arithmetic number, because the mean of its divisors is an integer number (9255225).

Almost surely, 2^68690921 is an apocalyptic number.

68690921 is the 5861-st centered square number.

It is an amenable number.

68690921 is a deficient number, since it is larger than the sum of its proper divisors (5350879).

68690921 is a wasteful number, since it uses less digits than its factorization.

68690921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4795.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 68690921 is about 8287.9986124516. The cubic root of 68690921 is about 409.5432569896.

The spelling of 68690921 in words is "sixty-eight million, six hundred ninety thousand, nine hundred twenty-one".