68490815557 has 4 divisors (see below), whose sum is σ = 70700196736. Its totient is φ = 66281434380.

The previous prime is 68490815539. The next prime is 68490815597. The reversal of 68490815557 is 75551809486.

It is a happy number.

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 68490815557 - 2²³ = 68482426949 is a prime.

It is the 261708-th Hogben number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68490815507) by changing a digit.

It is a nontrivial repunit in base 261707.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1104690543 + ... + 1104690604.

It is an arithmetic number, because the mean of its divisors is an integer number (17675049184).

Almost surely, 2^68490815557 is an apocalyptic number.

It is an amenable number.

68490815557 is a deficient number, since it is larger than the sum of its proper divisors (2209381179).

68490815557 is a wasteful number, since it uses less digits than its factorization.

68490815557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2209381178.

The product of its (nonzero) digits is 12096000, while the sum is 58.

The spelling of 68490815557 in words is "sixty-eight billion, four hundred ninety million, eight hundred fifteen thousand, five hundred fifty-seven".