28181431 has 4 divisors (see below), whose sum is σ = 28567552. Its totient is φ = 27795312.

The previous prime is 28181429. The next prime is 28181453. The reversal of 28181431 is 13418182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13418182 = 2 ⋅6709091.

It is a cyclic number.

It is not a de Polignac number, because 28181431 - 2¹ = 28181429 is a prime.

It is a super-2 number, since 2×28181431² = 1588386106415522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28181431.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28181471) 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, 192951 + ... + 193096.

It is an arithmetic number, because the mean of its divisors is an integer number (7141888).

Almost surely, 2^28181431 is an apocalyptic number.

28181431 is a deficient number, since it is larger than the sum of its proper divisors (386121).

28181431 is an equidigital number, since it uses as much as digits as its factorization.

28181431 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386120.

The product of its digits is 1536, while the sum is 28.

The square root of 28181431 is about 5308.6185585329. The cubic root of 28181431 is about 304.3133563378.

The spelling of 28181431 in words is "twenty-eight million, one hundred eighty-one thousand, four hundred thirty-one".