81265943841778 has 8 divisors (see below), whose sum is σ = 121918830650460. Its totient is φ = 40626333624960.

The previous prime is 81265943841763. The next prime is 81265943841781. The reversal of 81265943841778 is 87714834956218.

It can be written as a sum of positive squares in 2 ways, for example, as 80605256109849 + 660687731929 = 8978043^2 + 812827^2 .

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

It is a super-3 number, since 3×81265943841778³ (a number of 43 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81265943841778.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3319132663 + ... + 3319157146.

Almost surely, 2^{81265943841778} is an apocalyptic number.

81265943841778 is a deficient number, since it is larger than the sum of its proper divisors (40652886808682).

81265943841778 is a wasteful number, since it uses less digits than its factorization.

81265943841778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6638295932.

The product of its digits is 650280960, while the sum is 73.

The spelling of 81265943841778 in words is "eighty-one trillion, two hundred sixty-five billion, nine hundred forty-three million, eight hundred forty-one thousand, seven hundred seventy-eight".