78643643 has 12 divisors (see below), whose sum is σ = 86979168. Its totient is φ = 71042400.

The previous prime is 78643639. The next prime is 78643651. The reversal of 78643643 is 34634687.

It is not a de Polignac number, because 78643643 - 2² = 78643639 is a prime.

It is a super-2 number, since 2×78643643² = 12369645168622898, which 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 78643643.

It is not an unprimeable number, because it can be changed into a prime (78643613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2993 + ... + 12893.

It is an arithmetic number, because the mean of its divisors is an integer number (7248264).

Almost surely, 2^78643643 is an apocalyptic number.

78643643 is a deficient number, since it is larger than the sum of its proper divisors (8335525).

78643643 is a wasteful number, since it uses less digits than its factorization.

78643643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9974 (or 9961 counting only the distinct ones).

The product of its digits is 290304, while the sum is 41.

The square root of 78643643 is about 8868.1251118824. The cubic root of 78643643 is about 428.4378925183.

The spelling of 78643643 in words is "seventy-eight million, six hundred forty-three thousand, six hundred forty-three".