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78765613 = 731078981

78765613 has 4 divisors (see below), whose sum is σ = 79844668. Its totient is φ = 77686560.

The previous prime is 78765587. The next prime is 78765619. The reversal of 78765613 is 31656787.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31656787 = 65348479.

It can be written as a sum of positive squares in 2 ways, for example, as 13527684 + 65237929 = 3678^2 + 8077^2 .

It is a cyclic number.

It is not a de Polignac number, because 78765613 - 213 = 78757421 is a prime.

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 78765613.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78765619) 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, 539418 + ... + 539563.

It is an arithmetic number, because the mean of its divisors is an integer number (19961167).

Almost surely, 278765613 is an apocalyptic number.

78765613 is a gapful number since it is divisible by the number (73) formed by its first and last digit.

It is an amenable number.

78765613 is a deficient number, since it is larger than the sum of its proper divisors (1079055).

78765613 is a wasteful number, since it uses less digits than its factorization.

78765613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1079054.

The product of its digits is 211680, while the sum is 43.

The square root of 78765613 is about 8874.9993239436. Note that the first 3 decimals coincide. The cubic root of 78765613 is about 428.6592690795.

The spelling of 78765613 in words is "seventy-eight million, seven hundred sixty-five thousand, six hundred thirteen".

Divisors: 1 73 1078981 78765613