78244644781 has 4 divisors (see below), whose sum is σ = 82362784000. Its totient is φ = 74126505564.

The previous prime is 78244644767. The next prime is 78244644791. The reversal of 78244644781 is 18744644287.

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, and also an emirpimes, since its reverse is a distinct semiprime: 18744644287 = 241 ⋅77778607.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78244644781 is a prime.

It is a super-2 number, since 2×78244644781² (a number of 23 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 (78244644761) 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, 2059069581 + ... + 2059069618.

It is an arithmetic number, because the mean of its divisors is an integer number (20590696000).

Almost surely, 2^78244644781 is an apocalyptic number.

It is an amenable number.

78244644781 is a deficient number, since it is larger than the sum of its proper divisors (4118139219).

78244644781 is a wasteful number, since it uses less digits than its factorization.

78244644781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4118139218.

The product of its digits is 9633792, while the sum is 55.

The spelling of 78244644781 in words is "seventy-eight billion, two hundred forty-four million, six hundred forty-four thousand, seven hundred eighty-one".