28643531 has 4 divisors (see below), whose sum is σ = 32735472. Its totient is φ = 24551592.

The previous prime is 28643519. The next prime is 28643557. The reversal of 28643531 is 13534682.

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 28643531 - 2¹⁰ = 28642507 is a prime.

It is a super-2 number, since 2×28643531² = 1640903736295922, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28643731) 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, 2045960 + ... + 2045973.

It is an arithmetic number, because the mean of its divisors is an integer number (8183868).

Almost surely, 2^28643531 is an apocalyptic number.

28643531 is a deficient number, since it is larger than the sum of its proper divisors (4091941).

28643531 is an equidigital number, since it uses as much as digits as its factorization.

28643531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4091940.

The product of its digits is 17280, while the sum is 32.

The square root of 28643531 is about 5351.9651531003. The cubic root of 28643531 is about 305.9676550316.

The spelling of 28643531 in words is "twenty-eight million, six hundred forty-three thousand, five hundred thirty-one".