20500000 has 84 divisors (see below), whose sum is σ = 51679026. Its totient is φ = 8000000.

The previous prime is 20499971. The next prime is 20500019. The reversal of 20500000 is 502.

It can be written as a sum of positive squares in 7 ways, for example, as 16289296 + 4210704 = 4036^2 + 2052^2 .

It is a sliding number, since 20500000 = 500000 + 20000000 and 1/500000 + 1/20000000 = 0.0000020500000.

It is an unprimeable number.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 499980 + ... + 500020.

Almost surely, 2^20500000 is an apocalyptic number.

20500000 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 20500000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25839513).

20500000 is an abundant number, since it is smaller than the sum of its proper divisors (31179026).

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

20500000 is an frugal number, since it uses more digits than its factorization.

20500000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 10, while the sum is 7.

The square root of 20500000 is about 4527.6925690687. The cubic root of 20500000 is about 273.6851837399.

Adding to 20500000 its reverse (502), we get a palindrome (20500502).

It can be divided in two parts, 20 and 500000, that multiplied together give a 7-th power (10000000 = 10⁷).

The spelling of 20500000 in words is "twenty million, five hundred thousand".