19821821825 has 12 divisors (see below), whose sum is σ = 26469756348. Its totient is φ = 14637652800.

The previous prime is 19821821821. The next prime is 19821821849. The reversal of 19821821825 is 52812812891.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 7090987264 + 12730834561 = 84208^2 + 112831^2 .

It is not a de Polignac number, because 19821821825 - 2² = 19821821821 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 19821821825.

It is not an unprimeable number, because it can be changed into a prime (19821821821) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30494786 + ... + 30495435.

It is an arithmetic number, because the mean of its divisors is an integer number (2205813029).

Almost surely, 2^19821821825 is an apocalyptic number.

It is an amenable number.

19821821825 is a deficient number, since it is larger than the sum of its proper divisors (6647934523).

19821821825 is a wasteful number, since it uses less digits than its factorization.

19821821825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60990244 (or 60990239 counting only the distinct ones).

The product of its digits is 184320, while the sum is 47.

The spelling of 19821821825 in words is "nineteen billion, eight hundred twenty-one million, eight hundred twenty-one thousand, eight hundred twenty-five".