78399567421 has 16 divisors (see below), whose sum is σ = 90847728000. Its totient is φ = 66263885568.

The previous prime is 78399567397. The next prime is 78399567451. The reversal of 78399567421 is 12476599387.

It is a cyclic number.

It is not a de Polignac number, because 78399567421 - 2³³ = 69809632829 is a prime.

It is a super-2 number, since 2×78399567421² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78399567421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78399567451) 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 15 ways as a sum of consecutive naturals, for example, 2590545 + ... + 2620633.

It is an arithmetic number, because the mean of its divisors is an integer number (5677983000).

Almost surely, 2^78399567421 is an apocalyptic number.

It is an amenable number.

78399567421 is a deficient number, since it is larger than the sum of its proper divisors (12448160579).

78399567421 is a wasteful number, since it uses less digits than its factorization.

78399567421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35268.

The product of its digits is 22861440, while the sum is 61.

The spelling of 78399567421 in words is "seventy-eight billion, three hundred ninety-nine million, five hundred sixty-seven thousand, four hundred twenty-one".