2231721 has 24 divisors (see below), whose sum is σ = 3511040. Its totient is φ = 1360800.

The previous prime is 2231717. The next prime is 2231731. The reversal of 2231721 is 1271322.

It is not a de Polignac number, because 2231721 - 2² = 2231717 is a prime.

It is a super-3 number, since 3×2231721³ = 33345785707540855083, which contains 333 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2231694 and 2231703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2231711) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5091 + ... + 5511.

2^2231721 is an apocalyptic number.

It is an amenable number.

2231721 is a deficient number, since it is larger than the sum of its proper divisors (1279319).

2231721 is a wasteful number, since it uses less digits than its factorization.

2231721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477 (or 474 counting only the distinct ones).

The product of its digits is 168, while the sum is 18.

The square root of 2231721 is about 1493.8945745935. The cubic root of 2231721 is about 130.6812560356.

The spelling of 2231721 in words is "two million, two hundred thirty-one thousand, seven hundred twenty-one".