21040688 has 20 divisors (see below), whose sum is σ = 40838160. Its totient is φ = 10501824.

The previous prime is 21040687. The next prime is 21040697. The reversal of 21040688 is 88604012.

It is a self number, because there is not a number n which added to its sum of digits gives 21040688.

It is not an unprimeable number, because it can be changed into a prime (21040681) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15293 + ... + 16611.

It is an arithmetic number, because the mean of its divisors is an integer number (2041908).

Almost surely, 2^21040688 is an apocalyptic number.

It is an amenable number.

21040688 is a deficient number, since it is larger than the sum of its proper divisors (19797472).

21040688 is a wasteful number, since it uses less digits than its factorization.

21040688 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2324 (or 2318 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The square root of 21040688 is about 4587.0129714227. The cubic root of 21040688 is about 276.0704853934.

The spelling of 21040688 in words is "twenty-one million, forty thousand, six hundred eighty-eight".