21305736 has 48 divisors (see below), whose sum is σ = 58032000. Its totient is φ = 7061472.

The previous prime is 21305729. The next prime is 21305737. The reversal of 21305736 is 63750312.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21305737) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13585 + ... + 15071.

It is an arithmetic number, because the mean of its divisors is an integer number (1209000).

Almost surely, 2^21305736 is an apocalyptic number.

It is an amenable number.

21305736 is an abundant number, since it is smaller than the sum of its proper divisors (36726264).

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

21305736 is a wasteful number, since it uses less digits than its factorization.

21305736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1698 (or 1691 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21305736 is about 4615.8136877478. The cubic root of 21305736 is about 277.2248648697.

The spelling of 21305736 in words is "twenty-one million, three hundred five thousand, seven hundred thirty-six".