21203444 has 6 divisors (see below), whose sum is σ = 37106034. Its totient is φ = 10601720.

The previous prime is 21203431. The next prime is 21203459. The reversal of 21203444 is 44430212.

It can be written as a sum of positive squares in only one way, i.e., 17123044 + 4080400 = 4138^2 + 2020^2 .

It is a super-2 number, since 2×21203444² = 899172074922272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2650427 + ... + 2650434.

It is an arithmetic number, because the mean of its divisors is an integer number (6184339).

Almost surely, 2^21203444 is an apocalyptic number.

It is an amenable number.

21203444 is a deficient number, since it is larger than the sum of its proper divisors (15902590).

21203444 is a wasteful number, since it uses less digits than its factorization.

21203444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5300865 (or 5300863 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21203444 is about 4604.7197526017. The cubic root of 21203444 is about 276.7804870304.

Adding to 21203444 its reverse (44430212), we get a palindrome (65633656).

The spelling of 21203444 in words is "twenty-one million, two hundred three thousand, four hundred forty-four".