28403731 has 4 divisors (see below), whose sum is σ = 29383200. Its totient is φ = 27424264.

The previous prime is 28403729. The next prime is 28403741. The reversal of 28403731 is 13730482.

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 28403731 - 2¹ = 28403729 is a prime.

It is a super-2 number, since 2×28403731² = 1613543869440722, 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 28403731.

It is not an unprimeable number, because it can be changed into a prime (28403701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 489691 + ... + 489748.

It is an arithmetic number, because the mean of its divisors is an integer number (7345800).

Almost surely, 2^28403731 is an apocalyptic number.

28403731 is a deficient number, since it is larger than the sum of its proper divisors (979469).

28403731 is an equidigital number, since it uses as much as digits as its factorization.

28403731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 979468.

The product of its (nonzero) digits is 4032, while the sum is 28.

The square root of 28403731 is about 5329.5150811307. The cubic root of 28403731 is about 305.1114203685. Note that the first 3 decimals are identical.

The spelling of 28403731 in words is "twenty-eight million, four hundred three thousand, seven hundred thirty-one".