28620656640 has 520 divisors, whose sum is σ = 104471028288. Its totient is φ = 7524679680.

The previous prime is 28620656639. The next prime is 28620656641. The reversal of 28620656640 is 4665602682.

28620656640 is a `hidden beast` number, since 2 + 86 + 2 + 0 + 6 + 566 + 4 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (28620656639) and next prime (28620656641).

It is a super-3 number, since 3×28620656640³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (28620656641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 403107805 + ... + 403107875.

Almost surely, 2^28620656640 is an apocalyptic number.

28620656640 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 28620656640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (52235514144).

28620656640 is an abundant number, since it is smaller than the sum of its proper divisors (75850371648).

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

28620656640 is an frugal number, since it uses more digits than its factorization.

28620656640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 45.

The spelling of 28620656640 in words is "twenty-eight billion, six hundred twenty million, six hundred fifty-six thousand, six hundred forty".