21023444 has 24 divisors (see below), whose sum is σ = 39752328. Its totient is φ = 9671040.

The previous prime is 21023419. The next prime is 21023459. The reversal of 21023444 is 44432012.

It can be written as a sum of positive squares in 4 ways, for example, as 1768900 + 19254544 = 1330^2 + 4388^2 .

It is a super-2 number, since 2×21023444² = 883970395242272, 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 in 7 ways as a sum of consecutive naturals, for example, 23534 + ... + 24410.

It is an arithmetic number, because the mean of its divisors is an integer number (1656347).

Almost surely, 2^21023444 is an apocalyptic number.

It is an amenable number.

21023444 is a deficient number, since it is larger than the sum of its proper divisors (18728884).

21023444 is a wasteful number, since it uses less digits than its factorization.

21023444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1355 (or 1353 counting only the distinct ones).

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

The square root of 21023444 is about 4585.1329315517. The cubic root of 21023444 is about 275.9950464699.

Adding to 21023444 its reverse (44432012), we get a palindrome (65455456).

The spelling of 21023444 in words is "twenty-one million, twenty-three thousand, four hundred forty-four".