28909881420 has 576 divisors, whose sum is σ = 105373384704. Its totient is φ = 5875752960.

The previous prime is 28909881401. The next prime is 28909881443. The reversal of 28909881420 is 2418890982.

It is a happy number.

It is a super-2 number, since 2×28909881420² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 72820662 + ... + 72821058.

It is an arithmetic number, because the mean of its divisors is an integer number (182939904).

Almost surely, 2^28909881420 is an apocalyptic number.

28909881420 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 28909881420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52686692352).

28909881420 is an abundant number, since it is smaller than the sum of its proper divisors (76463503284).

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

28909881420 is a wasteful number, since it uses less digits than its factorization.

28909881420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 518 (or 509 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 51.

The spelling of 28909881420 in words is "twenty-eight billion, nine hundred nine million, eight hundred eighty-one thousand, four hundred twenty".