20511205550 has 48 divisors (see below), whose sum is σ = 43054275600. Its totient is φ = 7201420800.

The previous prime is 20511205529. The next prime is 20511205553. The reversal of 20511205550 is 5550211502.

It is a super-2 number, since 2×20511205550² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20511205553) 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, 627035 + ... + 658934.

It is an arithmetic number, because the mean of its divisors is an integer number (896964075).

Almost surely, 2^20511205550 is an apocalyptic number.

20511205550 is an abundant number, since it is smaller than the sum of its proper divisors (22543070050).

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

20511205550 is a wasteful number, since it uses less digits than its factorization.

20511205550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1286021 (or 1286016 counting only the distinct ones).

The product of its (nonzero) digits is 2500, while the sum is 26.

The spelling of 20511205550 in words is "twenty billion, five hundred eleven million, two hundred five thousand, five hundred fifty".