21489736 has 8 divisors (see below), whose sum is σ = 40293270. Its totient is φ = 10744864.

The previous prime is 21489731. The next prime is 21489737. The reversal of 21489736 is 63798412.

It can be written as a sum of positive squares in only one way, i.e., 13616100 + 7873636 = 3690^2 + 2806^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21489731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1343101 + ... + 1343116.

Almost surely, 2^21489736 is an apocalyptic number.

It is an amenable number.

21489736 is a deficient number, since it is larger than the sum of its proper divisors (18803534).

21489736 is a wasteful number, since it uses less digits than its factorization.

21489736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2686223 (or 2686219 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 21489736 is about 4635.7023200374. The cubic root of 21489736 is about 278.0206323213.

The spelling of 21489736 in words is "twenty-one million, four hundred eighty-nine thousand, seven hundred thirty-six".