20909391 has 8 divisors (see below), whose sum is σ = 27927984. Its totient is φ = 13915200.

The previous prime is 20909389. The next prime is 20909419. The reversal of 20909391 is 19390902.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20909391 - 2¹ = 20909389 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20909311) 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, 3996 + ... + 7601.

It is an arithmetic number, because the mean of its divisors is an integer number (3490998).

Almost surely, 2^20909391 is an apocalyptic number.

20909391 is a deficient number, since it is larger than the sum of its proper divisors (7018593).

20909391 is a wasteful number, since it uses less digits than its factorization.

20909391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12201.

The product of its (nonzero) digits is 4374, while the sum is 33.

The square root of 20909391 is about 4572.6787553905. The cubic root of 20909391 is about 275.4950465895.

The spelling of 20909391 in words is "twenty million, nine hundred nine thousand, three hundred ninety-one".