28917661 has 4 divisors (see below), whose sum is σ = 29325024. Its totient is φ = 28510300.

The previous prime is 28917653. The next prime is 28917671. The reversal of 28917661 is 16671982.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 16671982 = 2 ⋅8335991.

It is a cyclic number.

It is not a de Polignac number, because 28917661 - 2³ = 28917653 is a prime.

It is a super-2 number, since 2×28917661² = 1672462235421842, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28917641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 203575 + ... + 203716.

It is an arithmetic number, because the mean of its divisors is an integer number (7331256).

Almost surely, 2^28917661 is an apocalyptic number.

It is an amenable number.

28917661 is a deficient number, since it is larger than the sum of its proper divisors (407363).

28917661 is an equidigital number, since it uses as much as digits as its factorization.

28917661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407362.

The product of its digits is 36288, while the sum is 40.

The square root of 28917661 is about 5377.5143886372. The cubic root of 28917661 is about 306.9406351064.

The spelling of 28917661 in words is "twenty-eight million, nine hundred seventeen thousand, six hundred sixty-one".