3991157 has 4 divisors (see below), whose sum is σ = 4119936. Its totient is φ = 3862380.

The previous prime is 3991139. The next prime is 3991181. The reversal of 3991157 is 7511993.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 3991157 - 2⁶ = 3991093 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3990157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64343 + ... + 64404.

It is an arithmetic number, because the mean of its divisors is an integer number (1029984).

Almost surely, 2^3991157 is an apocalyptic number.

It is an amenable number.

3991157 is a deficient number, since it is larger than the sum of its proper divisors (128779).

3991157 is a wasteful number, since it uses less digits than its factorization.

3991157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128778.

The product of its digits is 8505, while the sum is 35.

The square root of 3991157 is about 1997.7880267936. The cubic root of 3991157 is about 158.6230406584.

The spelling of 3991157 in words is "three million, nine hundred ninety-one thousand, one hundred fifty-seven".