396717821 has 2 divisors, whose sum is σ = 396717822. Its totient is φ = 396717820.

The previous prime is 396717803. The next prime is 396717851. The reversal of 396717821 is 128717693.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 393427225 + 3290596 = 19835^2 + 1814^2 .

It is a cyclic number.

It is not a de Polignac number, because 396717821 - 2¹⁰ = 396716797 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (396717851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 198358910 + 198358911.

It is an arithmetic number, because the mean of its divisors is an integer number (198358911).

Almost surely, 2^396717821 is an apocalyptic number.

It is an amenable number.

396717821 is a deficient number, since it is larger than the sum of its proper divisors (1).

396717821 is an equidigital number, since it uses as much as digits as its factorization.

396717821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 127008, while the sum is 44.

The square root of 396717821 is about 19917.7765074317. The cubic root of 396717821 is about 734.7854872477.

The spelling of 396717821 in words is "three hundred ninety-six million, seven hundred seventeen thousand, eight hundred twenty-one".