2231821 has 2 divisors, whose sum is σ = 2231822. Its totient is φ = 2231820.

The previous prime is 2231819. The next prime is 2231833. The reversal of 2231821 is 1281322.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1929321 + 302500 = 1389^2 + 550^2 .

It is a cyclic number.

It is not a de Polignac number, because 2231821 - 2¹ = 2231819 is a prime.

It is a super-3 number, since 3×2231821³ = 33350268429158401983, which contains 333 as substring.

Together with 2231819, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2231861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1115910 + 1115911.

It is an arithmetic number, because the mean of its divisors is an integer number (1115911).

2^2231821 is an apocalyptic number.

It is an amenable number.

2231821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2231821 is an equidigital number, since it uses as much as digits as its factorization.

2231821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 192, while the sum is 19.

The square root of 2231821 is about 1493.9280437826. The cubic root of 2231821 is about 130.6832078821.

The spelling of 2231821 in words is "two million, two hundred thirty-one thousand, eight hundred twenty-one".