8215621 has 4 divisors (see below), whose sum is σ = 8416044. Its totient is φ = 8015200.

The previous prime is 8215601. The next prime is 8215633. The reversal of 8215621 is 1265128.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 297025 + 7918596 = 545^2 + 2814^2 .

It is a cyclic number.

It is not a de Polignac number, because 8215621 - 2¹³ = 8207429 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8215601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 100150 + ... + 100231.

It is an arithmetic number, because the mean of its divisors is an integer number (2104011).

Almost surely, 2^8215621 is an apocalyptic number.

It is an amenable number.

8215621 is a deficient number, since it is larger than the sum of its proper divisors (200423).

8215621 is a wasteful number, since it uses less digits than its factorization.

8215621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200422.

The product of its digits is 960, while the sum is 25.

The square root of 8215621 is about 2866.2904598104. The cubic root of 8215621 is about 201.7809359306.

It can be divided in two parts, 8215 and 621, that added together give a square (8836 = 94²).

The spelling of 8215621 in words is "eight million, two hundred fifteen thousand, six hundred twenty-one".