21536668 has 6 divisors (see below), whose sum is σ = 37689176. Its totient is φ = 10768332.

The previous prime is 21536657. The next prime is 21536687. The reversal of 21536668 is 86663512.

It is a super-3 number, since 3×21536668³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2692080 + ... + 2692087.

Almost surely, 2^21536668 is an apocalyptic number.

It is an amenable number.

21536668 is a deficient number, since it is larger than the sum of its proper divisors (16152508).

21536668 is a wasteful number, since it uses less digits than its factorization.

21536668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5384171 (or 5384169 counting only the distinct ones).

The product of its digits is 51840, while the sum is 37.

The square root of 21536668 is about 4640.7615754313. The cubic root of 21536668 is about 278.2228773552. Note that the first 3 decimals are identical.

The spelling of 21536668 in words is "twenty-one million, five hundred thirty-six thousand, six hundred sixty-eight".