3951981 has 36 divisors (see below), whose sum is σ = 6639360. Its totient is φ = 2257200.

The previous prime is 3951977. The next prime is 3951989. The reversal of 3951981 is 1891593.

It is a happy number.

It is not a de Polignac number, because 3951981 - 2² = 3951977 is a prime.

It is a super-2 number, since 2×3951981² = 31236307648722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3951989) 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 in 35 ways as a sum of consecutive naturals, for example, 20596 + ... + 20786.

Almost surely, 2^3951981 is an apocalyptic number.

It is an amenable number.

3951981 is a deficient number, since it is larger than the sum of its proper divisors (2687379).

3951981 is a wasteful number, since it uses less digits than its factorization.

3951981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238 (or 224 counting only the distinct ones).

The product of its digits is 9720, while the sum is 36.

The square root of 3951981 is about 1987.9590036014. The cubic root of 3951981 is about 158.1023344955.

The spelling of 3951981 in words is "three million, nine hundred fifty-one thousand, nine hundred eighty-one".