78746821 has 2 divisors, whose sum is σ = 78746822. Its totient is φ = 78746820.

The previous prime is 78746809. The next prime is 78746867. The reversal of 78746821 is 12864787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 48650625 + 30096196 = 6975^2 + 5486^2 .

It is a cyclic number.

It is not a de Polignac number, because 78746821 - 2²¹ = 76649669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78746891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39373410 + 39373411.

It is an arithmetic number, because the mean of its divisors is an integer number (39373411).

Almost surely, 2^78746821 is an apocalyptic number.

It is an amenable number.

78746821 is a deficient number, since it is larger than the sum of its proper divisors (1).

78746821 is an equidigital number, since it uses as much as digits as its factorization.

78746821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 150528, while the sum is 43.

The square root of 78746821 is about 8873.9405564833. The cubic root of 78746821 is about 428.6251763438.

The spelling of 78746821 in words is "seventy-eight million, seven hundred forty-six thousand, eight hundred twenty-one".