3721981 has 2 divisors, whose sum is σ = 3721982. Its totient is φ = 3721980.

The previous prime is 3721973. The next prime is 3722009. The reversal of 3721981 is 1891273.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3667225 + 54756 = 1915^2 + 234^2 .

It is an emirp because it is prime and its reverse (1891273) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 3721981 - 2³ = 3721973 is a prime.

It is a super-2 number, since 2×3721981² = 27706285128722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3721901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1860990 + 1860991.

It is an arithmetic number, because the mean of its divisors is an integer number (1860991).

Almost surely, 2^3721981 is an apocalyptic number.

It is an amenable number.

3721981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3721981 is an equidigital number, since it uses as much as digits as its factorization.

3721981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 31.

The square root of 3721981 is about 1929.2436341738. The cubic root of 3721981 is about 154.9737173612.

The spelling of 3721981 in words is "three million, seven hundred twenty-one thousand, nine hundred eighty-one".