28081731 has 4 divisors (see below), whose sum is σ = 37442312. Its totient is φ = 18721152.

The previous prime is 28081727. The next prime is 28081733. The reversal of 28081731 is 13718082.

It is a happy number.

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

It is not a de Polignac number, because 28081731 - 2² = 28081727 is a prime.

It is a super-2 number, since 2×28081731² = 1577167231912722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28081733) 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, 4680286 + ... + 4680291.

It is an arithmetic number, because the mean of its divisors is an integer number (9360578).

Almost surely, 2^28081731 is an apocalyptic number.

28081731 is a deficient number, since it is larger than the sum of its proper divisors (9360581).

28081731 is an equidigital number, since it uses as much as digits as its factorization.

28081731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9360580.

The product of its (nonzero) digits is 2688, while the sum is 30.

The square root of 28081731 is about 5299.2198482418. The cubic root of 28081731 is about 303.9540666692.

The spelling of 28081731 in words is "twenty-eight million, eighty-one thousand, seven hundred thirty-one".