21451323 has 32 divisors (see below), whose sum is σ = 31530240. Its totient is φ = 12925440.

The previous prime is 21451319. The next prime is 21451343. The reversal of 21451323 is 32315412.

It is not a de Polignac number, because 21451323 - 2² = 21451319 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21451323.

It is not an unprimeable number, because it can be changed into a prime (21451303) 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 in 31 ways as a sum of consecutive naturals, for example, 156511 + ... + 156647.

It is an arithmetic number, because the mean of its divisors is an integer number (985320).

Almost surely, 2^21451323 is an apocalyptic number.

21451323 is a deficient number, since it is larger than the sum of its proper divisors (10078917).

21451323 is a wasteful number, since it uses less digits than its factorization.

21451323 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267.

The product of its digits is 720, while the sum is 21.

The square root of 21451323 is about 4631.5572974972. The cubic root of 21451323 is about 277.8548791426.

Adding to 21451323 its reverse (32315412), we get a palindrome (53766735).

The spelling of 21451323 in words is "twenty-one million, four hundred fifty-one thousand, three hundred twenty-three".