3851991 has 48 divisors (see below), whose sum is σ = 6787872. Its totient is φ = 2073600.

The previous prime is 3851989. The next prime is 3851993. The reversal of 3851991 is 1991583.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (3851989) and next prime (3851993).

It is not a de Polignac number, because 3851991 - 2¹ = 3851989 is a prime.

It is an Ulam number.

3851991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3851993) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 52731 + ... + 52803.

It is an arithmetic number, because the mean of its divisors is an integer number (141414).

Almost surely, 2^3851991 is an apocalyptic number.

3851991 is a deficient number, since it is larger than the sum of its proper divisors (2935881).

3851991 is a wasteful number, since it uses less digits than its factorization.

3851991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 141 counting only the distinct ones).

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

The square root of 3851991 is about 1962.6489752373. The cubic root of 3851991 is about 156.7575334246.

The spelling of 3851991 in words is "three million, eight hundred fifty-one thousand, nine hundred ninety-one".