21055444 has 6 divisors (see below), whose sum is σ = 36847034. Its totient is φ = 10527720.

The previous prime is 21055429. The next prime is 21055451. The reversal of 21055444 is 44455012.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 13046544 + 8008900 = 3612^2 + 2830^2 .

It is a congruent number.

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 as a sum of consecutive naturals, namely, 2631927 + ... + 2631934.

Almost surely, 2^21055444 is an apocalyptic number.

It is an amenable number.

21055444 is a deficient number, since it is larger than the sum of its proper divisors (15791590).

21055444 is a wasteful number, since it uses less digits than its factorization.

21055444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5263865 (or 5263863 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

The square root of 21055444 is about 4588.6211436552. The cubic root of 21055444 is about 276.1350071136.

The spelling of 21055444 in words is "twenty-one million, fifty-five thousand, four hundred forty-four".