8381991 has 8 divisors (see below), whose sum is σ = 11278960. Its totient is φ = 5536512.

The previous prime is 8381987. The next prime is 8381993. The reversal of 8381991 is 1991838.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 8381991 - 2² = 8381987 is a prime.

It is a Duffinian number.

8381991 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8381993) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12490 + ... + 13143.

It is an arithmetic number, because the mean of its divisors is an integer number (1409870).

Almost surely, 2^8381991 is an apocalyptic number.

8381991 is a deficient number, since it is larger than the sum of its proper divisors (2896969).

8381991 is a wasteful number, since it uses less digits than its factorization.

8381991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25745.

The product of its digits is 15552, while the sum is 39.

The square root of 8381991 is about 2895.1668345710. The cubic root of 8381991 is about 203.1338953422.

The spelling of 8381991 in words is "eight million, three hundred eighty-one thousand, nine hundred ninety-one".