3971621 has 2 divisors, whose sum is σ = 3971622. Its totient is φ = 3971620.

The previous prime is 3971599. The next prime is 3971651. The reversal of 3971621 is 1261793.

3971621 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3496900 + 474721 = 1870^2 + 689^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3971621 is a prime.

It is a Chen prime.

It is a nialpdrome in base 14.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3971651) 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, 1985810 + 1985811.

It is an arithmetic number, because the mean of its divisors is an integer number (1985811).

Almost surely, 2^3971621 is an apocalyptic number.

It is an amenable number.

3971621 is a deficient number, since it is larger than the sum of its proper divisors (1).

3971621 is an equidigital number, since it uses as much as digits as its factorization.

3971621 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268, while the sum is 29.

The square root of 3971621 is about 1992.8926212920. The cubic root of 3971621 is about 158.3638067539.

The spelling of 3971621 in words is "three million, nine hundred seventy-one thousand, six hundred twenty-one".