28319261 has 4 divisors (see below), whose sum is σ = 28351392. Its totient is φ = 28287132.

The previous prime is 28319257. The next prime is 28319267. The reversal of 28319261 is 16291382.

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, and also an emirpimes, since its reverse is a distinct semiprime: 16291382 = 2 ⋅8145691.

It is a cyclic number.

It is not a de Polignac number, because 28319261 - 2² = 28319257 is a prime.

It is a super-2 number, since 2×28319261² = 1603961087172242, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28319267) 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, 14705 + ... + 16518.

It is an arithmetic number, because the mean of its divisors is an integer number (7087848).

Almost surely, 2^28319261 is an apocalyptic number.

It is an amenable number.

28319261 is a deficient number, since it is larger than the sum of its proper divisors (32131).

28319261 is an equidigital number, since it uses as much as digits as its factorization.

28319261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32130.

The product of its digits is 5184, while the sum is 32.

The square root of 28319261 is about 5321.5844445052. The cubic root of 28319261 is about 304.8086625776.

The spelling of 28319261 in words is "twenty-eight million, three hundred nineteen thousand, two hundred sixty-one".