20910091 has 4 divisors (see below), whose sum is σ = 20920032. Its totient is φ = 20900152.

The previous prime is 20910067. The next prime is 20910101. The reversal of 20910091 is 19001902.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20910091 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20910011) 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 in 3 ways as a sum of consecutive naturals, for example, 436 + ... + 6481.

It is an arithmetic number, because the mean of its divisors is an integer number (5230008).

Almost surely, 2^20910091 is an apocalyptic number.

20910091 is a deficient number, since it is larger than the sum of its proper divisors (9941).

20910091 is an equidigital number, since it uses as much as digits as its factorization.

20910091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9940.

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 20910091 is about 4572.7552963175. The cubic root of 20910091 is about 275.4981208761.

Adding to 20910091 its reverse (19001902), we get a palindrome (39911993).

The spelling of 20910091 in words is "twenty million, nine hundred ten thousand, ninety-one".