78506551 has 2 divisors, whose sum is σ = 78506552. Its totient is φ = 78506550.

The previous prime is 78506543. The next prime is 78506557. The reversal of 78506551 is 15560587.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78506551 - 2³ = 78506543 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78506551.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78506557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39253275 + 39253276.

It is an arithmetic number, because the mean of its divisors is an integer number (39253276).

Almost surely, 2^78506551 is an apocalyptic number.

78506551 is a deficient number, since it is larger than the sum of its proper divisors (1).

78506551 is an equidigital number, since it uses as much as digits as its factorization.

78506551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 42000, while the sum is 37.

The square root of 78506551 is about 8860.3922599397. The cubic root of 78506551 is about 428.1887960129.

The spelling of 78506551 in words is "seventy-eight million, five hundred six thousand, five hundred fifty-one".