20921023 has 2 divisors, whose sum is σ = 20921024. Its totient is φ = 20921022.

The previous prime is 20921009. The next prime is 20921027. The reversal of 20921023 is 32012902.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20921023 - 2⁹ = 20920511 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20921027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10460511 + 10460512.

It is an arithmetic number, because the mean of its divisors is an integer number (10460512).

Almost surely, 2^20921023 is an apocalyptic number.

20921023 is a deficient number, since it is larger than the sum of its proper divisors (1).

20921023 is an equidigital number, since it uses as much as digits as its factorization.

20921023 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 19.

The square root of 20921023 is about 4573.9504807114. The cubic root of 20921023 is about 275.5461235487.

Adding to 20921023 its reverse (32012902), we get a palindrome (52933925).

The spelling of 20921023 in words is "twenty million, nine hundred twenty-one thousand, twenty-three".