28123657 has 4 divisors (see below), whose sum is σ = 28188160. Its totient is φ = 28059156.

The previous prime is 28123651. The next prime is 28123673. The reversal of 28123657 is 75632182.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28123657 - 2²³ = 19735049 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28123651) 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, 31593 + ... + 32470.

It is an arithmetic number, because the mean of its divisors is an integer number (7047040).

Almost surely, 2^28123657 is an apocalyptic number.

It is an amenable number.

28123657 is a deficient number, since it is larger than the sum of its proper divisors (64503).

28123657 is an equidigital number, since it uses as much as digits as its factorization.

28123657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 64502.

The product of its digits is 20160, while the sum is 34.

The square root of 28123657 is about 5303.1742381332. The cubic root of 28123657 is about 304.1052591699.

It can be divided in two parts, 28 and 123657, that multiplied together give a triangular number (3462396 = T₂₆₃₁).

The spelling of 28123657 in words is "twenty-eight million, one hundred twenty-three thousand, six hundred fifty-seven".