21281023 has 8 divisors (see below), whose sum is σ = 21518640. Its totient is φ = 21045120.

The previous prime is 21281021. The next prime is 21281027. The reversal of 21281023 is 32018212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21281023 - 2¹ = 21281021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21281021) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54513 + ... + 54901.

It is an arithmetic number, because the mean of its divisors is an integer number (2689830).

Almost surely, 2^21281023 is an apocalyptic number.

21281023 is a deficient number, since it is larger than the sum of its proper divisors (237617).

21281023 is a wasteful number, since it uses less digits than its factorization.

21281023 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 857.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 21281023 is about 4613.1359182231. The cubic root of 21281023 is about 277.1176369587.

Adding to 21281023 its reverse (32018212), we get a palindrome (53299235).

The spelling of 21281023 in words is "twenty-one million, two hundred eighty-one thousand, twenty-three".