20305691 has 4 divisors (see below), whose sum is σ = 23206512. Its totient is φ = 17404872.

The previous prime is 20305673. The next prime is 20305693. The reversal of 20305691 is 19650302.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20305691 - 2¹⁰ = 20304667 is a prime.

20305691 is a modest number, since divided by 5691 gives 203 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20305691.

It is not an unprimeable number, because it can be changed into a prime (20305693) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1450400 + ... + 1450413.

It is an arithmetic number, because the mean of its divisors is an integer number (5801628).

Almost surely, 2^20305691 is an apocalyptic number.

20305691 is a deficient number, since it is larger than the sum of its proper divisors (2900821).

20305691 is an equidigital number, since it uses as much as digits as its factorization.

20305691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2900820.

The product of its (nonzero) digits is 1620, while the sum is 26.

The square root of 20305691 is about 4506.1836402881. The cubic root of 20305691 is about 272.8177299975.

Adding to 20305691 its reverse (19650302), we get a palindrome (39955993).

The spelling of 20305691 in words is "twenty million, three hundred five thousand, six hundred ninety-one".