3655921 has 2 divisors, whose sum is σ = 3655922. Its totient is φ = 3655920.

The previous prime is 3655907. The next prime is 3655937. The reversal of 3655921 is 1295563.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3629025 + 26896 = 1905^2 + 164^2 .

It is an emirp because it is prime and its reverse (1295563) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3655921 - 2⁷ = 3655793 is a prime.

It is not a weakly prime, because it can be changed into another prime (3655021) 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, 1827960 + 1827961.

It is an arithmetic number, because the mean of its divisors is an integer number (1827961).

Almost surely, 2^3655921 is an apocalyptic number.

It is an amenable number.

3655921 is a deficient number, since it is larger than the sum of its proper divisors (1).

3655921 is an equidigital number, since it uses as much as digits as its factorization.

3655921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 8100, while the sum is 31.

The square root of 3655921 is about 1912.0462860506. The cubic root of 3655921 is about 154.0513827528.

The spelling of 3655921 in words is "three million, six hundred fifty-five thousand, nine hundred twenty-one".