20111028400 has 60 divisors (see below), whose sum is σ = 48370205200. Its totient is φ = 8035511040.

The previous prime is 20111028389. The next prime is 20111028437. The reversal of 20111028400 is 482011102.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 340246 + ... + 394954.

Almost surely, 2^20111028400 is an apocalyptic number.

20111028400 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 20111028400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24185102600).

20111028400 is an abundant number, since it is smaller than the sum of its proper divisors (28259176800).

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

20111028400 is a wasteful number, since it uses less digits than its factorization.

20111028400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55646 (or 55635 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

Adding to 20111028400 its reverse (482011102), we get a palindrome (20593039502).

The spelling of 20111028400 in words is "twenty billion, one hundred eleven million, twenty-eight thousand, four hundred".