20511205220 has 48 divisors (see below), whose sum is σ = 47517321600. Its totient is φ = 7374808320.

The previous prime is 20511205201. The next prime is 20511205271. The reversal of 20511205220 is 2250211502.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 20511205192 and 20511205201.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 504200 + ... + 543359.

It is an arithmetic number, because the mean of its divisors is an integer number (989944200).

Almost surely, 2^20511205220 is an apocalyptic number.

20511205220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20511205220 is an abundant number, since it is smaller than the sum of its proper divisors (27006116380).

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

20511205220 is a wasteful number, since it uses less digits than its factorization.

20511205220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1047668 (or 1047666 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

Adding to 20511205220 its reverse (2250211502), we get a palindrome (22761416722).

The spelling of 20511205220 in words is "twenty billion, five hundred eleven million, two hundred five thousand, two hundred twenty".