28020581 has 8 divisors (see below), whose sum is σ = 28880760. Its totient is φ = 27165888.

The previous prime is 28020569. The next prime is 28020613. The reversal of 28020581 is 18502082.

It can be written as a sum of positive squares in 4 ways, for example, as 1136356 + 26884225 = 1066^2 + 5185^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 28020581 - 2²² = 23826277 is a prime.

It is a super-2 number, since 2×28020581² = 1570305919155122, 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 28020581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28020511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10535 + ... + 12923.

It is an arithmetic number, because the mean of its divisors is an integer number (3610095).

Almost surely, 2^28020581 is an apocalyptic number.

It is an amenable number.

28020581 is a deficient number, since it is larger than the sum of its proper divisors (860179).

28020581 is a wasteful number, since it uses less digits than its factorization.

28020581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2743.

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 28020581 is about 5293.4469866052. The cubic root of 28020581 is about 303.7332790109.

The spelling of 28020581 in words is "twenty-eight million, twenty thousand, five hundred eighty-one".