21320123 has 12 divisors (see below), whose sum is σ = 23860104. Its totient is φ = 18892800.

The previous prime is 21320107. The next prime is 21320183. The reversal of 21320123 is 32102312.

It is a happy number.

It is not a de Polignac number, because 21320123 - 2⁴ = 21320107 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21320098 and 21320107.

It is not an unprimeable number, because it can be changed into a prime (21320183) 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 11 ways as a sum of consecutive naturals, for example, 17915 + ... + 19067.

It is an arithmetic number, because the mean of its divisors is an integer number (1988342).

Almost surely, 2^21320123 is an apocalyptic number.

21320123 is a deficient number, since it is larger than the sum of its proper divisors (2539981).

21320123 is a wasteful number, since it uses less digits than its factorization.

21320123 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1246 (or 1205 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21320123 is about 4617.3718715304. The cubic root of 21320123 is about 277.2872508350.

Adding to 21320123 its reverse (32102312), we get a palindrome (53422435).

The spelling of 21320123 in words is "twenty-one million, three hundred twenty thousand, one hundred twenty-three".