821404247 has 2 divisors, whose sum is σ = 821404248. Its totient is φ = 821404246.

The previous prime is 821404217. The next prime is 821404253. The reversal of 821404247 is 742404128.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 821404247 - 2¹⁰ = 821403223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821404217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410702123 + 410702124.

It is an arithmetic number, because the mean of its divisors is an integer number (410702124).

Almost surely, 2^821404247 is an apocalyptic number.

821404247 is a deficient number, since it is larger than the sum of its proper divisors (1).

821404247 is an equidigital number, since it uses as much as digits as its factorization.

821404247 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 14336, while the sum is 32.

The square root of 821404247 is about 28660.1508544529. The cubic root of 821404247 is about 936.5241508551.

The spelling of 821404247 in words is "eight hundred twenty-one million, four hundred four thousand, two hundred forty-seven".