28681531 has 2 divisors, whose sum is σ = 28681532. Its totient is φ = 28681530.

The previous prime is 28681517. The next prime is 28681577. The reversal of 28681531 is 13518682.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28681531 - 2⁷ = 28681403 is a prime.

It is a super-2 number, since 2×28681531² = 1645260441007922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (28681511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14340765 + 14340766.

It is an arithmetic number, because the mean of its divisors is an integer number (14340766).

Almost surely, 2^28681531 is an apocalyptic number.

28681531 is a deficient number, since it is larger than the sum of its proper divisors (1).

28681531 is an equidigital number, since it uses as much as digits as its factorization.

28681531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 34.

The square root of 28681531 is about 5355.5140742976. The cubic root of 28681531 is about 306.1028994505.

The spelling of 28681531 in words is "twenty-eight million, six hundred eighty-one thousand, five hundred thirty-one".