21865744 has 10 divisors (see below), whose sum is σ = 42364910. Its totient is φ = 10932864.

The previous prime is 21865741. The next prime is 21865759. The reversal of 21865744 is 44756812.

It can be written as a sum of positive squares in only one way, i.e., 17539344 + 4326400 = 4188^2 + 2080^2 .

It is a super-2 number, since 2×21865744² = 956221521347072, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21865741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 683289 + ... + 683320.

It is an arithmetic number, because the mean of its divisors is an integer number (4236491).

Almost surely, 2^21865744 is an apocalyptic number.

It is an amenable number.

21865744 is a deficient number, since it is larger than the sum of its proper divisors (20499166).

21865744 is a wasteful number, since it uses less digits than its factorization.

21865744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1366617 (or 1366611 counting only the distinct ones).

The product of its digits is 53760, while the sum is 37.

The square root of 21865744 is about 4676.0821207502. The cubic root of 21865744 is about 279.6327839179.

The spelling of 21865744 in words is "twenty-one million, eight hundred sixty-five thousand, seven hundred forty-four".