1025808821 has 2 divisors, whose sum is σ = 1025808822. Its totient is φ = 1025808820.

The previous prime is 1025808787. The next prime is 1025808859. The reversal of 1025808821 is 1288085201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 694059025 + 331749796 = 26345^2 + 18214^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1025808821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1025808871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 512904410 + 512904411.

It is an arithmetic number, because the mean of its divisors is an integer number (512904411).

Almost surely, 2^1025808821 is an apocalyptic number.

It is an amenable number.

1025808821 is a deficient number, since it is larger than the sum of its proper divisors (1).

1025808821 is an equidigital number, since it uses as much as digits as its factorization.

1025808821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10240, while the sum is 35.

The square root of 1025808821 is about 32028.2503580823. The cubic root of 1025808821 is about 1008.5299730122.

The spelling of 1025808821 in words is "one billion, twenty-five million, eight hundred eight thousand, eight hundred twenty-one".