21123310 has 48 divisors (see below), whose sum is σ = 42690240. Its totient is φ = 7512960.

The previous prime is 21123301. The next prime is 21123313. The reversal of 21123310 is 1332112.

It is a super-2 number, since 2×21123310² = 892388450712200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (13).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48795 + ... + 49225.

It is an arithmetic number, because the mean of its divisors is an integer number (889380).

Almost surely, 2^21123310 is an apocalyptic number.

21123310 is an abundant number, since it is smaller than the sum of its proper divisors (21566930).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21123310 is a wasteful number, since it uses less digits than its factorization.

21123310 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493 (or 480 counting only the distinct ones).

The product of its (nonzero) digits is 36, while the sum is 13.

The square root of 21123310 is about 4596.0102262723. The cubic root of 21123310 is about 276.4313687876.

Adding to 21123310 its reverse (1332112), we get a palindrome (22455422).

The spelling of 21123310 in words is "twenty-one million, one hundred twenty-three thousand, three hundred ten".