3991965 has 16 divisors (see below), whose sum is σ = 6543936. Its totient is φ = 2076800.

The previous prime is 3991961. The next prime is 3991973. The reversal of 3991965 is 5691993.

It is not a de Polignac number, because 3991965 - 2² = 3991961 is a prime.

It is a super-2 number, since 2×3991965² = 31871569122450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991961) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2631 + ... + 3860.

It is an arithmetic number, because the mean of its divisors is an integer number (408996).

Almost surely, 2^3991965 is an apocalyptic number.

It is an amenable number.

3991965 is a deficient number, since it is larger than the sum of its proper divisors (2551971).

3991965 is a wasteful number, since it uses less digits than its factorization.

3991965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6540.

The product of its digits is 65610, while the sum is 42.

The square root of 3991965 is about 1997.9902402164. The cubic root of 3991965 is about 158.6337442187.

The spelling of 3991965 in words is "three million, nine hundred ninety-one thousand, nine hundred sixty-five".