21015023 has 2 divisors, whose sum is σ = 21015024. Its totient is φ = 21015022.

The previous prime is 21015017. The next prime is 21015041. The reversal of 21015023 is 32051012.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21015023 is a prime.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 21014989 and 21015007.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21015013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10507511 + 10507512.

It is an arithmetic number, because the mean of its divisors is an integer number (10507512).

Almost surely, 2^21015023 is an apocalyptic number.

21015023 is a deficient number, since it is larger than the sum of its proper divisors (1).

21015023 is an equidigital number, since it uses as much as digits as its factorization.

21015023 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 14.

The square root of 21015023 is about 4584.2145455901. The cubic root of 21015023 is about 275.9581913497.

Adding to 21015023 its reverse (32051012), we get a palindrome (53066035).

The spelling of 21015023 in words is "twenty-one million, fifteen thousand, twenty-three".