3991155 has 16 divisors (see below), whose sum is σ = 7298304. Its totient is φ = 1824480.

The previous prime is 3991139. The next prime is 3991181. The reversal of 3991155 is 5511993.

It is not a de Polignac number, because 3991155 - 2⁴ = 3991139 is a prime.

It is an Ulam number.

It is a zygodrome in base 2.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18901 + ... + 19110.

It is an arithmetic number, because the mean of its divisors is an integer number (456144).

Almost surely, 2^3991155 is an apocalyptic number.

3991155 is a gapful number since it is divisible by the number (35) formed by its first and last digit.

3991155 is a deficient number, since it is larger than the sum of its proper divisors (3307149).

3991155 is a wasteful number, since it uses less digits than its factorization.

3991155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38026.

The product of its digits is 6075, while the sum is 33.

The square root of 3991155 is about 1997.7875262400. The cubic root of 3991155 is about 158.6230141626.

The spelling of 3991155 in words is "three million, nine hundred ninety-one thousand, one hundred fifty-five".