7211820 has 144 divisors (see below), whose sum is σ = 25740288. Its totient is φ = 1491840.

The previous prime is 7211803. The next prime is 7211839. The reversal of 7211820 is 281127.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32229 + ... + 32451.

It is an arithmetic number, because the mean of its divisors is an integer number (178752).

Almost surely, 2^7211820 is an apocalyptic number.

7211820 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7211820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12870144).

7211820 is an abundant number, since it is smaller than the sum of its proper divisors (18528468).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7211820 is a wasteful number, since it uses less digits than its factorization.

7211820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 260 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 21.

The square root of 7211820 is about 2685.4831967450. The cubic root of 7211820 is about 193.2034865995.

Adding to 7211820 its reverse (281127), we get a palindrome (7492947).

The spelling of 7211820 in words is "seven million, two hundred eleven thousand, eight hundred twenty".