20928391 has 12 divisors (see below), whose sum is σ = 23189400. Its totient is φ = 18730880.

The previous prime is 20928373. The next prime is 20928407. The reversal of 20928391 is 19382902.

It is not a de Polignac number, because 20928391 - 2⁵ = 20928359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20928361) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140385 + ... + 140533.

It is an arithmetic number, because the mean of its divisors is an integer number (1932450).

Almost surely, 2^20928391 is an apocalyptic number.

20928391 is a deficient number, since it is larger than the sum of its proper divisors (2261009).

20928391 is a wasteful number, since it uses less digits than its factorization.

20928391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 20928391 is about 4574.7558404794. The cubic root of 20928391 is about 275.5784671797.

The spelling of 20928391 in words is "twenty million, nine hundred twenty-eight thousand, three hundred ninety-one".