20688887 has 4 divisors (see below), whose sum is σ = 21193536. Its totient is φ = 20184240.

The previous prime is 20688869. The next prime is 20688907. The reversal of 20688887 is 78888602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20688887 - 2¹² = 20684791 is a prime.

It is a super-3 number, since 3×20688887³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20688817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 252263 + ... + 252344.

It is an arithmetic number, because the mean of its divisors is an integer number (5298384).

Almost surely, 2^20688887 is an apocalyptic number.

20688887 is a deficient number, since it is larger than the sum of its proper divisors (504649).

20688887 is an equidigital number, since it uses as much as digits as its factorization.

20688887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 504648.

The product of its (nonzero) digits is 344064, while the sum is 47.

The square root of 20688887 is about 4548.5038199390. The cubic root of 20688887 is about 274.5231936058.

The spelling of 20688887 in words is "twenty million, six hundred eighty-eight thousand, eight hundred eighty-seven".