40185385781 has 4 divisors (see below), whose sum is σ = 40216562700. Its totient is φ = 40154208864.

The previous prime is 40185385763. The next prime is 40185385787. The reversal of 40185385781 is 18758358104.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 24493815025 + 15691570756 = 156505^2 + 125266^2 .

It is a cyclic number.

It is not a de Polignac number, because 40185385781 - 2⁶ = 40185385717 is a prime.

It is a super-2 number, since 2×40185385781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (40185385787) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15586526 + ... + 15589103.

It is an arithmetic number, because the mean of its divisors is an integer number (10054140675).

Almost surely, 2^40185385781 is an apocalyptic number.

It is an amenable number.

40185385781 is a deficient number, since it is larger than the sum of its proper divisors (31176919).

40185385781 is a wasteful number, since it uses less digits than its factorization.

40185385781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31176918.

The product of its (nonzero) digits is 1075200, while the sum is 50.

The spelling of 40185385781 in words is "forty billion, one hundred eighty-five million, three hundred eighty-five thousand, seven hundred eighty-one".