21123450 has 48 divisors (see below), whose sum is σ = 58210560. Its totient is φ = 5632560.

The previous prime is 21123391. The next prime is 21123457. The reversal of 21123450 is 5432112.

21123450 is a `hidden beast` number, since 211 + 2 + 3 + 450 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21123457) 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, 6474 + ... + 9173.

It is an arithmetic number, because the mean of its divisors is an integer number (1212720).

Almost surely, 2^21123450 is an apocalyptic number.

21123450 is an abundant number, since it is smaller than the sum of its proper divisors (37087110).

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

21123450 is a wasteful number, since it uses less digits than its factorization.

21123450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15668 (or 15657 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21123450 is about 4596.0254568486. The cubic root of 21123450 is about 276.4319794922.

Adding to 21123450 its reverse (5432112), we get a palindrome (26555562).

The spelling of 21123450 in words is "twenty-one million, one hundred twenty-three thousand, four hundred fifty".