20688516 has 36 divisors (see below), whose sum is σ = 53158924. Its totient is φ = 6782400.

The previous prime is 20688463. The next prime is 20688517. The reversal of 20688516 is 61588602.

It is a happy number.

20688516 is nontrivially palindromic in base 13.

It can be written as a sum of positive squares in 2 ways, for example, as 3048516 + 17640000 = 1746^2 + 4200^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20688517) by changing a digit.

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 in 11 ways as a sum of consecutive naturals, for example, 2515 + ... + 6906.

Almost surely, 2^20688516 is an apocalyptic number.

It is an amenable number.

20688516 is an abundant number, since it is smaller than the sum of its proper divisors (32470408).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20688516 is a wasteful number, since it uses less digits than its factorization.

20688516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9492 (or 9487 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 36.

The square root of 20688516 is about 4548.4630371148. The cubic root of 20688516 is about 274.5215526490.

The spelling of 20688516 in words is "twenty million, six hundred eighty-eight thousand, five hundred sixteen".