21789736 has 8 divisors (see below), whose sum is σ = 40855770. Its totient is φ = 10894864.

The previous prime is 21789727. The next prime is 21789739. The reversal of 21789736 is 63798712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21436900 + 352836 = 4630^2 + 594^2 .

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

It is a junction number, because it is equal to n+sod(n) for n = 21789692 and 21789701.

It is not an unprimeable number, because it can be changed into a prime (21789739) 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, 1361851 + ... + 1361866.

Almost surely, 2^21789736 is an apocalyptic number.

It is an amenable number.

21789736 is a deficient number, since it is larger than the sum of its proper divisors (19066034).

21789736 is a wasteful number, since it uses less digits than its factorization.

21789736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2723723 (or 2723719 counting only the distinct ones).

The product of its digits is 127008, while the sum is 43.

The square root of 21789736 is about 4667.9477289276. The cubic root of 21789736 is about 279.3083951715.

The spelling of 21789736 in words is "twenty-one million, seven hundred eighty-nine thousand, seven hundred thirty-six".