8457991 has 4 divisors (see below), whose sum is σ = 8465184. Its totient is φ = 8450800.

The previous prime is 8457989. The next prime is 8458001. The reversal of 8457991 is 1997548.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 8457991 - 2¹ = 8457989 is a prime.

It is a super-2 number, since 2×8457991² = 143075223512162, which contains 22 as substring.

It is a Duffinian number.

8457991 is a lucky number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8457901) 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, 1375 + ... + 4336.

It is an arithmetic number, because the mean of its divisors is an integer number (2116296).

Almost surely, 2^8457991 is an apocalyptic number.

8457991 is a deficient number, since it is larger than the sum of its proper divisors (7193).

8457991 is a wasteful number, since it uses less digits than its factorization.

8457991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7192.

The product of its digits is 90720, while the sum is 43.

The square root of 8457991 is about 2908.2625397306. The cubic root of 8457991 is about 203.7459913648.

It can be divided in two parts, 845 and 7991, that added together give a square (8836 = 94²).

The spelling of 8457991 in words is "eight million, four hundred fifty-seven thousand, nine hundred ninety-one".