21135023 has 12 divisors (see below), whose sum is σ = 26477640. Its totient is φ = 16721712.

The previous prime is 21135013. The next prime is 21135031. The reversal of 21135023 is 32053112.

It is not a de Polignac number, because 21135023 - 2¹² = 21130927 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21134992 and 21135010.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135013) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15953 + ... + 17226.

It is an arithmetic number, because the mean of its divisors is an integer number (2206470).

Almost surely, 2^21135023 is an apocalyptic number.

21135023 is a deficient number, since it is larger than the sum of its proper divisors (5342617).

21135023 is a wasteful number, since it uses less digits than its factorization.

21135023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33206 (or 33199 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 17.

The square root of 21135023 is about 4597.2843070665. The cubic root of 21135023 is about 276.4824536214.

Adding to 21135023 its reverse (32053112), we get a palindrome (53188135).

The spelling of 21135023 in words is "twenty-one million, one hundred thirty-five thousand, twenty-three".