3728821 has 2 divisors, whose sum is σ = 3728822. Its totient is φ = 3728820.

The previous prime is 3728789. The next prime is 3728861. The reversal of 3728821 is 1288273.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2002225 + 1726596 = 1415^2 + 1314^2 .

It is a cyclic number.

It is not a de Polignac number, because 3728821 - 2⁵ = 3728789 is a prime.

It is a d-powerful number, because it can be written as 3¹³ + 7⁴ + 2⁷ + 8⁵ + 8⁷ + 2¹¹ + 1 .

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3728861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1864410 + 1864411.

It is an arithmetic number, because the mean of its divisors is an integer number (1864411).

Almost surely, 2^3728821 is an apocalyptic number.

It is an amenable number.

3728821 is a deficient number, since it is larger than the sum of its proper divisors (1).

3728821 is an equidigital number, since it uses as much as digits as its factorization.

3728821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5376, while the sum is 31.

The square root of 3728821 is about 1931.0155359292. The cubic root of 3728821 is about 155.0685926032.

The spelling of 3728821 in words is "three million, seven hundred twenty-eight thousand, eight hundred twenty-one".