825921821 has 2 divisors, whose sum is σ = 825921822. Its totient is φ = 825921820.

The previous prime is 825921791. The next prime is 825921823. The reversal of 825921821 is 128129528.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 824493796 + 1428025 = 28714^2 + 1195^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-825921821 is a prime.

Together with 825921823, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (825921823) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 412960910 + 412960911.

It is an arithmetic number, because the mean of its divisors is an integer number (412960911).

Almost surely, 2^825921821 is an apocalyptic number.

It is an amenable number.

825921821 is a deficient number, since it is larger than the sum of its proper divisors (1).

825921821 is an equidigital number, since it uses as much as digits as its factorization.

825921821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 23040, while the sum is 38.

The square root of 825921821 is about 28738.8555965613. The cubic root of 825921821 is about 938.2379170631.

The spelling of 825921821 in words is "eight hundred twenty-five million, nine hundred twenty-one thousand, eight hundred twenty-one".