28724581 has 2 divisors, whose sum is σ = 28724582. Its totient is φ = 28724580.

The previous prime is 28724503. The next prime is 28724603. The reversal of 28724581 is 18542782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14699556 + 14025025 = 3834^2 + 3745^2 .

It is a cyclic number.

It is not a de Polignac number, because 28724581 - 2²¹ = 26627429 is a prime.

It is a super-2 number, since 2×28724581² = 1650203107251122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28724581.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28724081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14362290 + 14362291.

It is an arithmetic number, because the mean of its divisors is an integer number (14362291).

Almost surely, 2^28724581 is an apocalyptic number.

It is an amenable number.

28724581 is a deficient number, since it is larger than the sum of its proper divisors (1).

28724581 is an equidigital number, since it uses as much as digits as its factorization.

28724581 is an evil number, because the sum of its binary digits is even.

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

The square root of 28724581 is about 5359.5317892517. The cubic root of 28724581 is about 306.2559728948.

The spelling of 28724581 in words is "twenty-eight million, seven hundred twenty-four thousand, five hundred eighty-one".