20690231 has 2 divisors, whose sum is σ = 20690232. Its totient is φ = 20690230.

The previous prime is 20690227. The next prime is 20690251. The reversal of 20690231 is 13209602.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20690231 - 2² = 20690227 is a prime.

It is a super-2 number, since 2×20690231² = 856171317666722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 20690197 and 20690206.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20690251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10345115 + 10345116.

It is an arithmetic number, because the mean of its divisors is an integer number (10345116).

Almost surely, 2^20690231 is an apocalyptic number.

20690231 is a deficient number, since it is larger than the sum of its proper divisors (1).

20690231 is an equidigital number, since it uses as much as digits as its factorization.

20690231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 648, while the sum is 23.

The square root of 20690231 is about 4548.6515584292. The cubic root of 20690231 is about 274.5291380400.

Adding to 20690231 its reverse (13209602), we get a palindrome (33899833).

The spelling of 20690231 in words is "twenty million, six hundred ninety thousand, two hundred thirty-one".