20689578 has 96 divisors (see below), whose sum is σ = 58496256. Its totient is φ = 5128704.

The previous prime is 20689523. The next prime is 20689583. The reversal of 20689578 is 87598602.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 27475 + ... + 28217.

It is an arithmetic number, because the mean of its divisors is an integer number (609336).

Almost surely, 2^20689578 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20689578, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29248128).

20689578 is an abundant number, since it is smaller than the sum of its proper divisors (37806678).

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

20689578 is a wasteful number, since it uses less digits than its factorization.

20689578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 788 (or 785 counting only the distinct ones).

The product of its (nonzero) digits is 241920, while the sum is 45.

The square root of 20689578 is about 4548.5797783484. The cubic root of 20689578 is about 274.5262498910.

The spelling of 20689578 in words is "twenty million, six hundred eighty-nine thousand, five hundred seventy-eight".