21158224 has 10 divisors (see below), whose sum is σ = 40994090. Its totient is φ = 10579104.

The previous prime is 21158201. The next prime is 21158231. The reversal of 21158224 is 42285112.

It can be written as a sum of positive squares in only one way, i.e., 20866624 + 291600 = 4568^2 + 540^2 .

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, 661179 + ... + 661210.

It is an arithmetic number, because the mean of its divisors is an integer number (4099409).

Almost surely, 2^21158224 is an apocalyptic number.

It is an amenable number.

21158224 is a deficient number, since it is larger than the sum of its proper divisors (19835866).

21158224 is a wasteful number, since it uses less digits than its factorization.

21158224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1322397 (or 1322391 counting only the distinct ones).

The product of its digits is 1280, while the sum is 25.

The square root of 21158224 is about 4599.8069524709. The cubic root of 21158224 is about 276.5835862863.

The spelling of 21158224 in words is "twenty-one million, one hundred fifty-eight thousand, two hundred twenty-four".