8391021 has 8 divisors (see below), whose sum is σ = 11674560. Its totient is φ = 5350752.

The previous prime is 8391011. The next prime is 8391023. The reversal of 8391021 is 1201938.

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

It is not a de Polignac number, because 8391021 - 2¹⁵ = 8358253 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 8390982 and 8391000.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8391023) 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, 60736 + ... + 60873.

It is an arithmetic number, because the mean of its divisors is an integer number (1459320).

Almost surely, 2^8391021 is an apocalyptic number.

It is an amenable number.

8391021 is a deficient number, since it is larger than the sum of its proper divisors (3283539).

8391021 is a wasteful number, since it uses less digits than its factorization.

8391021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121635.

The product of its (nonzero) digits is 432, while the sum is 24.

The square root of 8391021 is about 2896.7259104030. The cubic root of 8391021 is about 203.2068151996.

Adding to 8391021 its reverse (1201938), we get a palindrome (9592959).

The spelling of 8391021 in words is "eight million, three hundred ninety-one thousand, twenty-one".