78276987391 has 4 divisors (see below), whose sum is σ = 78995125000. Its totient is φ = 77558849784.

The previous prime is 78276987389. The next prime is 78276987401. The reversal of 78276987391 is 19378967287.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 78276987391 - 2¹ = 78276987389 is a prime.

It is a super-2 number, since 2×78276987391² (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 (78276987791) 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, 359068641 + ... + 359068858.

It is an arithmetic number, because the mean of its divisors is an integer number (19748781250).

Almost surely, 2^78276987391 is an apocalyptic number.

78276987391 is a deficient number, since it is larger than the sum of its proper divisors (718137609).

78276987391 is a wasteful number, since it uses less digits than its factorization.

78276987391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 718137608.

The product of its digits is 64012032, while the sum is 67.

The spelling of 78276987391 in words is "seventy-eight billion, two hundred seventy-six million, nine hundred eighty-seven thousand, three hundred ninety-one".