20071691 has 2 divisors, whose sum is σ = 20071692. Its totient is φ = 20071690.

The previous prime is 20071687. The next prime is 20071693. The reversal of 20071691 is 19617002.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20071691 - 2² = 20071687 is a prime.

Together with 20071693, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20071691.

It is not a weakly prime, because it can be changed into another prime (20071693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10035845 + 10035846.

It is an arithmetic number, because the mean of its divisors is an integer number (10035846).

Almost surely, 2^20071691 is an apocalyptic number.

20071691 is a deficient number, since it is larger than the sum of its proper divisors (1).

20071691 is an equidigital number, since it uses as much as digits as its factorization.

20071691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 756, while the sum is 26.

The square root of 20071691 is about 4480.1440825045. The cubic root of 20071691 is about 271.7657070900.

Adding to 20071691 its reverse (19617002), we get a palindrome (39688693).

The spelling of 20071691 in words is "twenty million, seventy-one thousand, six hundred ninety-one".