28215765 has 12 divisors (see below), whose sum is σ = 48907404. Its totient is φ = 15048384.

The previous prime is 28215763. The next prime is 28215791. The reversal of 28215765 is 56751282.

It is a happy number.

28215765 is a `hidden beast` number, since 2 + 82 + 1 + 576 + 5 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7064964 + 21150801 = 2658^2 + 4599^2 .

It is not a de Polignac number, because 28215765 - 2¹ = 28215763 is a prime.

It is a super-2 number, since 2×28215765² = 1592258789070450, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28215763) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 313464 + ... + 313553.

It is an arithmetic number, because the mean of its divisors is an integer number (4075617).

Almost surely, 2^28215765 is an apocalyptic number.

It is an amenable number.

28215765 is a deficient number, since it is larger than the sum of its proper divisors (20691639).

28215765 is a wasteful number, since it uses less digits than its factorization.

28215765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 627028 (or 627025 counting only the distinct ones).

The product of its digits is 33600, while the sum is 36.

The square root of 28215765 is about 5311.8513721677. The cubic root of 28215765 is about 304.4368898627.

The spelling of 28215765 in words is "twenty-eight million, two hundred fifteen thousand, seven hundred sixty-five".