7213821 has 8 divisors (see below), whose sum is σ = 9633120. Its totient is φ = 4801872.

The previous prime is 7213819. The next prime is 7213841. The reversal of 7213821 is 1283127.

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

It is not a de Polignac number, because 7213821 - 2¹ = 7213819 is a prime.

It is a Curzon number.

It is a nialpdrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 7213791 and 7213800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7213841) 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, 1150 + ... + 3968.

It is an arithmetic number, because the mean of its divisors is an integer number (1204140).

Almost surely, 2^7213821 is an apocalyptic number.

It is an amenable number.

7213821 is a deficient number, since it is larger than the sum of its proper divisors (2419299).

7213821 is a wasteful number, since it uses less digits than its factorization.

7213821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3675.

The product of its digits is 672, while the sum is 24.

The square root of 7213821 is about 2685.8557295581. The cubic root of 7213821 is about 193.2213537688.

Adding to 7213821 its reverse (1283127), we get a palindrome (8496948).

The spelling of 7213821 in words is "seven million, two hundred thirteen thousand, eight hundred twenty-one".