20505312 has 96 divisors (see below), whose sum is σ = 60752160. Its totient is φ = 6811776.

The previous prime is 20505307. The next prime is 20505341. The reversal of 20505312 is 21350502.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69838 + ... + 70130.

It is an arithmetic number, because the mean of its divisors is an integer number (632835).

Almost surely, 2^20505312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20505312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30376080).

20505312 is an abundant number, since it is smaller than the sum of its proper divisors (40246848).

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

20505312 is an frugal number, since it uses more digits than its factorization.

20505312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324 (or 298 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 18.

The square root of 20505312 is about 4528.2791433391. The cubic root of 20505312 is about 273.7088209780.

Adding to 20505312 its reverse (21350502), we get a palindrome (41855814).

The spelling of 20505312 in words is "twenty million, five hundred five thousand, three hundred twelve".