21163684 has 6 divisors (see below), whose sum is σ = 37036454. Its totient is φ = 10581840.

The previous prime is 21163643. The next prime is 21163687. The reversal of 21163684 is 48636112.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 20884900 + 278784 = 4570^2 + 528^2 .

It is not an unprimeable number, because it can be changed into a prime (21163687) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2645457 + ... + 2645464.

Almost surely, 2^21163684 is an apocalyptic number.

It is an amenable number.

21163684 is a deficient number, since it is larger than the sum of its proper divisors (15872770).

21163684 is a wasteful number, since it uses less digits than its factorization.

21163684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5290925 (or 5290923 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21163684 is about 4600.4004173550. The cubic root of 21163684 is about 276.6073755624.

Adding to 21163684 its reverse (48636112), we get a palindrome (69799796).

The spelling of 21163684 in words is "twenty-one million, one hundred sixty-three thousand, six hundred eighty-four".