821061491 has 2 divisors, whose sum is σ = 821061492. Its totient is φ = 821061490.

The previous prime is 821061473. The next prime is 821061511. The reversal of 821061491 is 194160128.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 821061491 - 2¹⁰ = 821060467 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (821061091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410530745 + 410530746.

It is an arithmetic number, because the mean of its divisors is an integer number (410530746).

Almost surely, 2^821061491 is an apocalyptic number.

821061491 is a deficient number, since it is larger than the sum of its proper divisors (1).

821061491 is an equidigital number, since it uses as much as digits as its factorization.

821061491 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 32.

The square root of 821061491 is about 28654.1705690463. The cubic root of 821061491 is about 936.3938683004.

The spelling of 821061491 in words is "eight hundred twenty-one million, sixty-one thousand, four hundred ninety-one".