21713684 has 6 divisors (see below), whose sum is σ = 37998954. Its totient is φ = 10856840.

The previous prime is 21713683. The next prime is 21713693. The reversal of 21713684 is 48631712.

It can be written as a sum of positive squares in only one way, i.e., 20340100 + 1373584 = 4510^2 + 1172^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21713684.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21713683) 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, 2714207 + ... + 2714214.

It is an arithmetic number, because the mean of its divisors is an integer number (6333159).

Almost surely, 2^21713684 is an apocalyptic number.

It is an amenable number.

21713684 is a deficient number, since it is larger than the sum of its proper divisors (16285270).

21713684 is a wasteful number, since it uses less digits than its factorization.

21713684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5428425 (or 5428423 counting only the distinct ones).

The product of its digits is 8064, while the sum is 32.

The square root of 21713684 is about 4659.7944160660. The cubic root of 21713684 is about 278.9830627385.

The spelling of 21713684 in words is "twenty-one million, seven hundred thirteen thousand, six hundred eighty-four".