20505100 has 72 divisors (see below), whose sum is σ = 55496448. Its totient is φ = 6388800.

The previous prime is 20505097. The next prime is 20505101. The reversal of 20505100 is 150502.

It is not an unprimeable number, because it can be changed into a prime (20505101) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 6369 + ... + 9031.

It is an arithmetic number, because the mean of its divisors is an integer number (770784).

Almost surely, 2^20505100 is an apocalyptic number.

20505100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20505100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27748224).

20505100 is an abundant number, since it is smaller than the sum of its proper divisors (34991348).

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

20505100 is a wasteful number, since it uses less digits than its factorization.

20505100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2695 (or 2688 counting only the distinct ones).

The product of its (nonzero) digits is 50, while the sum is 13.

The square root of 20505100 is about 4528.2557348277. The cubic root of 20505100 is about 273.7078777026.

Adding to 20505100 its reverse (150502), we get a palindrome (20655602).

The spelling of 20505100 in words is "twenty million, five hundred five thousand, one hundred".