3991878 has 24 divisors (see below), whose sum is σ = 9435816. Its totient is φ = 1209600.

The previous prime is 3991877. The next prime is 3991891. The reversal of 3991878 is 8781993.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (3991877) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9883 + ... + 10278.

It is an arithmetic number, because the mean of its divisors is an integer number (393159).

Almost surely, 2^3991878 is an apocalyptic number.

3991878 is an abundant number, since it is smaller than the sum of its proper divisors (5443938).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

3991878 is a wasteful number, since it uses less digits than its factorization.

3991878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20180 (or 20177 counting only the distinct ones).

The product of its digits is 108864, while the sum is 45.

The square root of 3991878 is about 1997.9684682197. The cubic root of 3991878 is about 158.6325918008.

The spelling of 3991878 in words is "three million, nine hundred ninety-one thousand, eight hundred seventy-eight".