28720232220 has 24 divisors (see below), whose sum is σ = 80416650384. Its totient is φ = 7658728576.

The previous prime is 28720232183. The next prime is 28720232231. The reversal of 28720232220 is 2223202782.

It is a super-2 number, since 2×28720232220² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 239335209 + ... + 239335328.

It is an arithmetic number, because the mean of its divisors is an integer number (3350693766).

Almost surely, 2^28720232220 is an apocalyptic number.

28720232220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28720232220 is an abundant number, since it is smaller than the sum of its proper divisors (51696418164).

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

28720232220 is a wasteful number, since it uses less digits than its factorization.

28720232220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 478670549 (or 478670547 counting only the distinct ones).

The product of its (nonzero) digits is 10752, while the sum is 30.

The spelling of 28720232220 in words is "twenty-eight billion, seven hundred twenty million, two hundred thirty-two thousand, two hundred twenty".