28311556 has 72 divisors (see below), whose sum is σ = 63619584. Its totient is φ = 10782720.

The previous prime is 28311553. The next prime is 28311557. The reversal of 28311556 is 65511382.

It is a super-2 number, since 2×28311556² = 1603088406282272, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28311553) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 146596 + ... + 146788.

Almost surely, 2^28311556 is an apocalyptic number.

28311556 is a gapful number since it is divisible by the number (26) 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 28311556, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31809792).

28311556 is an abundant number, since it is smaller than the sum of its proper divisors (35308028).

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

28311556 is a wasteful number, since it uses less digits than its factorization.

28311556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261 (or 246 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 28311556 is about 5320.8604567307. The cubic root of 28311556 is about 304.7810163316.

28311556 divided by its sum of digits (31) gives a triangular number (913276 = T₁₃₅₁).

The spelling of 28311556 in words is "twenty-eight million, three hundred eleven thousand, five hundred fifty-six".