28910921 has 8 divisors (see below), whose sum is σ = 31859520. Its totient is φ = 26065872.

The previous prime is 28910909. The next prime is 28910923. The reversal of 28910921 is 12901982.

It is a happy number.

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 28910921 - 2²² = 24716617 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28910923) 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, 25301 + ... + 26418.

It is an arithmetic number, because the mean of its divisors is an integer number (3982440).

Almost surely, 2^28910921 is an apocalyptic number.

It is an amenable number.

28910921 is a deficient number, since it is larger than the sum of its proper divisors (2948599).

28910921 is a wasteful number, since it uses less digits than its factorization.

28910921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51775.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 28910921 is about 5376.8876685309. The cubic root of 28910921 is about 306.9167864668.

The spelling of 28910921 in words is "twenty-eight million, nine hundred ten thousand, nine hundred twenty-one".