20506500 has 288 divisors, whose sum is σ = 79672320. Its totient is φ = 4536000.

The previous prime is 20506487. The next prime is 20506513. The reversal of 20506500 is 560502.

20506500 = 155² + 156² + ... + 402².

It is an interprime number because it is at equal distance from previous prime (20506487) and next prime (20506513).

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 polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 661485 + ... + 661515.

It is an arithmetic number, because the mean of its divisors is an integer number (276640).

Almost surely, 2^20506500 is an apocalyptic number.

20506500 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 20506500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39836160).

20506500 is an abundant number, since it is smaller than the sum of its proper divisors (59165820).

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

20506500 is a wasteful number, since it uses less digits than its factorization.

20506500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73 (or 48 counting only the distinct ones).

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

The square root of 20506500 is about 4528.4103170980. The cubic root of 20506500 is about 273.7141067596.

The spelling of 20506500 in words is "twenty million, five hundred six thousand, five hundred".