20997311 has 2 divisors, whose sum is σ = 20997312. Its totient is φ = 20997310.

The previous prime is 20997293. The next prime is 20997313. The reversal of 20997311 is 11379902.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20997311 is a prime.

Together with 20997313, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20997313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10498655 + 10498656.

It is an arithmetic number, because the mean of its divisors is an integer number (10498656).

Almost surely, 2^20997311 is an apocalyptic number.

20997311 is a deficient number, since it is larger than the sum of its proper divisors (1).

20997311 is an equidigital number, since it uses as much as digits as its factorization.

20997311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3402, while the sum is 32.

The square root of 20997311 is about 4582.2822916097. The cubic root of 20997311 is about 275.8806413464.

The spelling of 20997311 in words is "twenty million, nine hundred ninety-seven thousand, three hundred eleven".