8402521 has 4 divisors (see below), whose sum is σ = 8767872. Its totient is φ = 8037172.

The previous prime is 8402509. The next prime is 8402531. The reversal of 8402521 is 1252048.

8402521 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 8402521 - 2²³ = 13913 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 8402492 and 8402501.

It is not an unprimeable number, because it can be changed into a prime (8402531) 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, 182641 + ... + 182686.

It is an arithmetic number, because the mean of its divisors is an integer number (2191968).

Almost surely, 2^8402521 is an apocalyptic number.

It is an amenable number.

8402521 is a deficient number, since it is larger than the sum of its proper divisors (365351).

8402521 is a wasteful number, since it uses less digits than its factorization.

8402521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 365350.

The product of its (nonzero) digits is 640, while the sum is 22.

The square root of 8402521 is about 2898.7102304301. The cubic root of 8402521 is about 203.2996053227.

Adding to 8402521 its reverse (1252048), we get a palindrome (9654569).

The spelling of 8402521 in words is "eight million, four hundred two thousand, five hundred twenty-one".