68405503781 has 4 divisors (see below), whose sum is σ = 68406028332. Its totient is φ = 68404979232.

The previous prime is 68405503769. The next prime is 68405503801. The reversal of 68405503781 is 18730550486.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 2557324900 + 65848178881 = 50570^2 + 256609^2 .

It is a cyclic number.

It is not a de Polignac number, because 68405503781 - 2²² = 68401309477 is a prime.

It is a super-2 number, since 2×68405503781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (68405503081) 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, 101795 + ... + 383631.

It is an arithmetic number, because the mean of its divisors is an integer number (17101507083).

Almost surely, 2^68405503781 is an apocalyptic number.

It is an amenable number.

68405503781 is a deficient number, since it is larger than the sum of its proper divisors (524551).

68405503781 is a wasteful number, since it uses less digits than its factorization.

68405503781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 524550.

The product of its (nonzero) digits is 806400, while the sum is 47.

The spelling of 68405503781 in words is "sixty-eight billion, four hundred five million, five hundred three thousand, seven hundred eighty-one".