20688061 has 4 divisors (see below), whose sum is σ = 20701792.
Its totient is φ = 20674332.
The previous prime is 20688043. The next prime is 20688071. The reversal of 20688061 is 16088602.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.
It is a cyclic number.
It is not a de Polignac number, because 20688061 - 29 = 20687549 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (20688001) 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, 4281 + ... + 7726.
It is an arithmetic number, because the mean of its divisors is an integer number (5175448).
Almost surely, 220688061 is an apocalyptic number.
It is an amenable number.
20688061 is a deficient number, since it is larger than the sum of its proper divisors (13731).
20688061 is a wasteful number, since it uses less digits than its factorization.
20688061 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 13730.
The product of its (nonzero) digits is 4608, while the sum is 31.
The square root of 20688061 is about 4548.4130199444.
The cubic root of 20688061 is about 274.5195401279.
The spelling of 20688061 in words is "twenty million, six hundred eighty-eight thousand, sixty-one".