78521671 has 2 divisors, whose sum is σ = 78521672. Its totient is φ = 78521670.

The previous prime is 78521621. The next prime is 78521689. The reversal of 78521671 is 17612587.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 78521671 - 2²¹ = 76424519 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 78521671.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78521621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39260835 + 39260836.

It is an arithmetic number, because the mean of its divisors is an integer number (39260836).

Almost surely, 2^78521671 is an apocalyptic number.

78521671 is a deficient number, since it is larger than the sum of its proper divisors (1).

78521671 is an equidigital number, since it uses as much as digits as its factorization.

78521671 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23520, while the sum is 37.

The square root of 78521671 is about 8861.2454542237. The cubic root of 78521671 is about 428.2162833114.

The spelling of 78521671 in words is "seventy-eight million, five hundred twenty-one thousand, six hundred seventy-one".