78821629 has 2 divisors, whose sum is σ = 78821630. Its totient is φ = 78821628.

The previous prime is 78821599. The next prime is 78821641. The reversal of 78821629 is 92612887.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62805625 + 16016004 = 7925^2 + 4002^2 .

It is a cyclic number.

It is not a de Polignac number, because 78821629 - 2⁹ = 78821117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (78821669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39410814 + 39410815.

It is an arithmetic number, because the mean of its divisors is an integer number (39410815).

Almost surely, 2^78821629 is an apocalyptic number.

It is an amenable number.

78821629 is a deficient number, since it is larger than the sum of its proper divisors (1).

78821629 is an equidigital number, since it uses as much as digits as its factorization.

78821629 is an evil number, because the sum of its binary digits is even.

The product of its digits is 96768, while the sum is 43.

The square root of 78821629 is about 8878.1545942837. The cubic root of 78821629 is about 428.7608620073.

It can be divided in two parts, 7882 and 1629, that multiplied together give a triangular number (12839778 = T₅₀₆₇).

The spelling of 78821629 in words is "seventy-eight million, eight hundred twenty-one thousand, six hundred twenty-nine".