821461549 has 2 divisors, whose sum is σ = 821461550. Its totient is φ = 821461548.

The previous prime is 821461547. The next prime is 821461601. The reversal of 821461549 is 945164128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 729972324 + 91489225 = 27018^2 + 9565^2 .

It is a cyclic number.

It is not a de Polignac number, because 821461549 - 2¹ = 821461547 is a prime.

Together with 821461547, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (821461547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410730774 + 410730775.

It is an arithmetic number, because the mean of its divisors is an integer number (410730775).

Almost surely, 2^821461549 is an apocalyptic number.

It is an amenable number.

821461549 is a deficient number, since it is larger than the sum of its proper divisors (1).

821461549 is an equidigital number, since it uses as much as digits as its factorization.

821461549 is an evil number, because the sum of its binary digits is even.

The product of its digits is 69120, while the sum is 40.

The square root of 821461549 is about 28661.1505177304. The cubic root of 821461549 is about 936.5459279761.

The spelling of 821461549 in words is "eight hundred twenty-one million, four hundred sixty-one thousand, five hundred forty-nine".