28180661 has 2 divisors, whose sum is σ = 28180662. Its totient is φ = 28180660.

The previous prime is 28180657. The next prime is 28180673. The reversal of 28180661 is 16608182.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28143025 + 37636 = 5305^2 + 194^2 .

It is a cyclic number.

It is not a de Polignac number, because 28180661 - 2² = 28180657 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28180601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14090330 + 14090331.

It is an arithmetic number, because the mean of its divisors is an integer number (14090331).

Almost surely, 2^28180661 is an apocalyptic number.

It is an amenable number.

28180661 is a deficient number, since it is larger than the sum of its proper divisors (1).

28180661 is an equidigital number, since it uses as much as digits as its factorization.

28180661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 28180661 is about 5308.5460344618. The cubic root of 28180661 is about 304.3105847324.

The spelling of 28180661 in words is "twenty-eight million, one hundred eighty thousand, six hundred sixty-one".