21708244 has 6 divisors (see below), whose sum is σ = 37989434. Its totient is φ = 10854120.

The previous prime is 21708223. The next prime is 21708263. The reversal of 21708244 is 44280712.

It can be written as a sum of positive squares in only one way, i.e., 18818244 + 2890000 = 4338^2 + 1700^2 .

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, 2713527 + ... + 2713534.

Almost surely, 2^21708244 is an apocalyptic number.

It is an amenable number.

21708244 is a deficient number, since it is larger than the sum of its proper divisors (16281190).

21708244 is a wasteful number, since it uses less digits than its factorization.

21708244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5427065 (or 5427063 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 28.

The square root of 21708244 is about 4659.2106627625. The cubic root of 21708244 is about 278.9597626141.

Adding to 21708244 its reverse (44280712), we get a palindrome (65988956).

It can be divided in two parts, 21708 and 244, that added together give a cube (21952 = 28³).

The spelling of 21708244 in words is "twenty-one million, seven hundred eight thousand, two hundred forty-four".