28158623 has 4 divisors (see below), whose sum is σ = 29129640. Its totient is φ = 27187608.

The previous prime is 28158617. The next prime is 28158649. The reversal of 28158623 is 32685182.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28158623 - 2¹⁰ = 28157599 is a prime.

It is a super-2 number, since 2×28158623² = 1585816098512258, 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 (28158673) 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, 485465 + ... + 485522.

It is an arithmetic number, because the mean of its divisors is an integer number (7282410).

Almost surely, 2^28158623 is an apocalyptic number.

28158623 is a deficient number, since it is larger than the sum of its proper divisors (971017).

28158623 is an equidigital number, since it uses as much as digits as its factorization.

28158623 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 971016.

The product of its digits is 23040, while the sum is 35.

The square root of 28158623 is about 5306.4699188820. The cubic root of 28158623 is about 304.2312378165.

It can be divided in two parts, 28 and 158623, that multiplied together give a palindrome (4441444).

The spelling of 28158623 in words is "twenty-eight million, one hundred fifty-eight thousand, six hundred twenty-three".