1647421813 has 2 divisors, whose sum is σ = 1647421814. Its totient is φ = 1647421812.

The previous prime is 1647421757. The next prime is 1647421817. The reversal of 1647421813 is 3181247461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1044129969 + 603291844 = 32313^2 + 24562^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1647421813 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1647421817) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823710906 + 823710907.

It is an arithmetic number, because the mean of its divisors is an integer number (823710907).

Almost surely, 2^1647421813 is an apocalyptic number.

It is an amenable number.

1647421813 is a deficient number, since it is larger than the sum of its proper divisors (1).

1647421813 is an equidigital number, since it uses as much as digits as its factorization.

1647421813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 37.

The square root of 1647421813 is about 40588.4443284046. Note that the first 3 decimals coincide. The cubic root of 1647421813 is about 1181.0499639138.

The spelling of 1647421813 in words is "one billion, six hundred forty-seven million, four hundred twenty-one thousand, eight hundred thirteen".