28239681 has 8 divisors (see below), whose sum is σ = 39634720. Its totient is φ = 17835552.

The previous prime is 28239641. The next prime is 28239683. The reversal of 28239681 is 18693282.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28239681 - 2¹⁷ = 28108609 is a prime.

It is a super-2 number, since 2×28239681² = 1594959165963522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28239683) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 247660 + ... + 247773.

It is an arithmetic number, because the mean of its divisors is an integer number (4954340).

Almost surely, 2^28239681 is an apocalyptic number.

It is an amenable number.

28239681 is a deficient number, since it is larger than the sum of its proper divisors (11395039).

28239681 is a wasteful number, since it uses less digits than its factorization.

28239681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495455.

The product of its digits is 41472, while the sum is 39.

The square root of 28239681 is about 5314.1020878414. The cubic root of 28239681 is about 304.5228802833.

It can be divided in two parts, 28239 and 681, that added together give a triangular number (28920 = T₂₄₀).

The spelling of 28239681 in words is "twenty-eight million, two hundred thirty-nine thousand, six hundred eighty-one".