19821601 has 2 divisors, whose sum is σ = 19821602. Its totient is φ = 19821600.

The previous prime is 19821589. The next prime is 19821623. The reversal of 19821601 is 10612891.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16192576 + 3629025 = 4024^2 + 1905^2 .

It is a cyclic number.

It is not a de Polignac number, because 19821601 - 2⁵ = 19821569 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 19821601.

It is not a weakly prime, because it can be changed into another prime (19821631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9910800 + 9910801.

It is an arithmetic number, because the mean of its divisors is an integer number (9910801).

Almost surely, 2^19821601 is an apocalyptic number.

It is an amenable number.

19821601 is a deficient number, since it is larger than the sum of its proper divisors (1).

19821601 is an equidigital number, since it uses as much as digits as its factorization.

19821601 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 28.

The square root of 19821601 is about 4452.1456624868. The cubic root of 19821601 is about 270.6322676712.

The spelling of 19821601 in words is "nineteen million, eight hundred twenty-one thousand, six hundred one".