812578643 has 4 divisors (see below), whose sum is σ = 855345960. Its totient is φ = 769811328.

The previous prime is 812578619. The next prime is 812578667. The reversal of 812578643 is 346875218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 346875218 = 2 ⋅173437609.

It is an interprime number because it is at equal distance from previous prime (812578619) and next prime (812578667).

It is a cyclic number.

It is not a de Polignac number, because 812578643 - 2⁸ = 812578387 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 812578594 and 812578603.

It is not an unprimeable number, because it can be changed into a prime (812578673) 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, 21383630 + ... + 21383667.

It is an arithmetic number, because the mean of its divisors is an integer number (213836490).

Almost surely, 2^812578643 is an apocalyptic number.

812578643 is a deficient number, since it is larger than the sum of its proper divisors (42767317).

812578643 is a wasteful number, since it uses less digits than its factorization.

812578643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42767316.

The product of its digits is 322560, while the sum is 44.

The square root of 812578643 is about 28505.7650835756. The cubic root of 812578643 is about 933.1578944766.

It can be divided in two parts, 8125 and 78643, that added together give a palindrome (86768).

The spelling of 812578643 in words is "eight hundred twelve million, five hundred seventy-eight thousand, six hundred forty-three".