28012720 has 20 divisors (see below), whose sum is σ = 65129760. Its totient is φ = 11205056.

The previous prime is 28012711. The next prime is 28012723. The reversal of 28012720 is 2721082.

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 28012691 and 28012700.

It is not an unprimeable number, because it can be changed into a prime (28012723) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175000 + ... + 175159.

It is an arithmetic number, because the mean of its divisors is an integer number (3256488).

Almost surely, 2^28012720 is an apocalyptic number.

28012720 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28012720 is an abundant number, since it is smaller than the sum of its proper divisors (37117040).

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

28012720 is a wasteful number, since it uses less digits than its factorization.

28012720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 350172 (or 350166 counting only the distinct ones).

The product of its (nonzero) digits is 448, while the sum is 22.

The square root of 28012720 is about 5292.7044126798. The cubic root of 28012720 is about 303.7048728592.

The spelling of 28012720 in words is "twenty-eight million, twelve thousand, seven hundred twenty".