68405521 has 4 divisors (see below), whose sum is σ = 68569200. Its totient is φ = 68241844.

The previous prime is 68405509. The next prime is 68405527. The reversal of 68405521 is 12550486.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 68405521 - 2¹⁵ = 68372753 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (68405527) 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, 81211 + ... + 82048.

It is an arithmetic number, because the mean of its divisors is an integer number (17142300).

Almost surely, 2^68405521 is an apocalyptic number.

It is an amenable number.

68405521 is a deficient number, since it is larger than the sum of its proper divisors (163679).

68405521 is a wasteful number, since it uses less digits than its factorization.

68405521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 163678.

The product of its (nonzero) digits is 9600, while the sum is 31.

The square root of 68405521 is about 8270.7630240504. The cubic root of 68405521 is about 408.9752736410.

The spelling of 68405521 in words is "sixty-eight million, four hundred five thousand, five hundred twenty-one".