678806621 has 2 divisors, whose sum is σ = 678806622. Its totient is φ = 678806620.

The previous prime is 678806599. The next prime is 678806627. The reversal of 678806621 is 126608876.

678806621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 655872100 + 22934521 = 25610^2 + 4789^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-678806621 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (678806627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 339403310 + 339403311.

It is an arithmetic number, because the mean of its divisors is an integer number (339403311).

Almost surely, 2^678806621 is an apocalyptic number.

It is an amenable number.

678806621 is a deficient number, since it is larger than the sum of its proper divisors (1).

678806621 is an equidigital number, since it uses as much as digits as its factorization.

678806621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 193536, while the sum is 44.

The square root of 678806621 is about 26053.9175749061. The cubic root of 678806621 is about 878.8512131881.

The spelling of 678806621 in words is "six hundred seventy-eight million, eight hundred six thousand, six hundred twenty-one".