21502144 has 28 divisors (see below), whose sum is σ = 45180504. Its totient is φ = 10118144.

The previous prime is 21502123. The next prime is 21502157. The reversal of 21502144 is 44120512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8794 + ... + 10969.

Almost surely, 2^21502144 is an apocalyptic number.

It is an amenable number.

21502144 is an abundant number, since it is smaller than the sum of its proper divisors (23678360).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21502144 is a wasteful number, since it uses less digits than its factorization.

21502144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19792 (or 19782 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21502144 is about 4637.0404354502. The cubic root of 21502144 is about 278.0741309819.

Adding to 21502144 its reverse (44120512), we get a palindrome (65622656).

The spelling of 21502144 in words is "twenty-one million, five hundred two thousand, one hundred forty-four".