21247144 has 16 divisors (see below), whose sum is σ = 42182100. Its totient is φ = 9998592.

The previous prime is 21247133. The next prime is 21247151. The reversal of 21247144 is 44174212.

It can be written as a sum of positive squares in 2 ways, for example, as 20702500 + 544644 = 4550^2 + 738^2 .

It is a super-2 number, since 2×21247144² = 902882256313472, 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 3 ways as a sum of consecutive naturals, for example, 77979 + ... + 78250.

Almost surely, 2^21247144 is an apocalyptic number.

It is an amenable number.

21247144 is a deficient number, since it is larger than the sum of its proper divisors (20934956).

21247144 is a wasteful number, since it uses less digits than its factorization.

21247144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 156252 (or 156248 counting only the distinct ones).

The product of its digits is 1792, while the sum is 25.

The square root of 21247144 is about 4609.4624415435. The cubic root of 21247144 is about 276.9705034473.

The spelling of 21247144 in words is "twenty-one million, two hundred forty-seven thousand, one hundred forty-four".