21201688 has 8 divisors (see below), whose sum is σ = 39753180. Its totient is φ = 10600840.

The previous prime is 21201679. The next prime is 21201689. The reversal of 21201688 is 88610212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201689) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1325098 + ... + 1325113.

Almost surely, 2^21201688 is an apocalyptic number.

It is an amenable number.

21201688 is a deficient number, since it is larger than the sum of its proper divisors (18551492).

21201688 is a wasteful number, since it uses less digits than its factorization.

21201688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2650217 (or 2650213 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 28.

The square root of 21201688 is about 4604.5290747263. The cubic root of 21201688 is about 276.7728461340.

The spelling of 21201688 in words is "twenty-one million, two hundred one thousand, six hundred eighty-eight".