28742581 has 4 divisors (see below), whose sum is σ = 32848672. Its totient is φ = 24636492.

The previous prime is 28742569. The next prime is 28742587. The reversal of 28742581 is 18524782.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18524782 = 2 ⋅9262391.

It is a cyclic number.

It is not a de Polignac number, because 28742581 - 2⁷ = 28742453 is a prime.

It is a super-2 number, since 2×28742581² = 1652271925083122, 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 28742581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28742587) 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, 2053035 + ... + 2053048.

It is an arithmetic number, because the mean of its divisors is an integer number (8212168).

Almost surely, 2^28742581 is an apocalyptic number.

It is an amenable number.

28742581 is a deficient number, since it is larger than the sum of its proper divisors (4106091).

28742581 is an equidigital number, since it uses as much as digits as its factorization.

28742581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4106090.

The product of its digits is 35840, while the sum is 37.

The square root of 28742581 is about 5361.2107774271. The cubic root of 28742581 is about 306.3199303863.

The spelling of 28742581 in words is "twenty-eight million, seven hundred forty-two thousand, five hundred eighty-one".