3901981 has 2 divisors, whose sum is σ = 3901982. Its totient is φ = 3901980.

The previous prime is 3901967. The next prime is 3901999. The reversal of 3901981 is 1891093.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 3118756 + 783225 = 1766^2 + 885^2 .

It is a cyclic number.

It is not a de Polignac number, because 3901981 - 2⁷ = 3901853 is a prime.

It is a super-2 number, since 2×3901981² = 30450911448722, which contains 22 as substring.

It is equal to p₂₇₆₇₃₆ and since 3901981 and 276736 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3901901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1950990 + 1950991.

It is an arithmetic number, because the mean of its divisors is an integer number (1950991).

Almost surely, 2^3901981 is an apocalyptic number.

It is an amenable number.

3901981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3901981 is an equidigital number, since it uses as much as digits as its factorization.

3901981 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 3901981 is about 1975.3432613093. The cubic root of 3901981 is about 157.4327385594.

The spelling of 3901981 in words is "three million, nine hundred one thousand, nine hundred eighty-one".