21042450 has 192 divisors, whose sum is σ = 68745600. Its totient is φ = 4665600.

The previous prime is 21042449. The next prime is 21042457. The reversal of 21042450 is 5424012.

21042450 is a `hidden beast` number, since 210 + 4 + 2 + 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 (21042457) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 192996 + ... + 193104.

It is an arithmetic number, because the mean of its divisors is an integer number (358050).

Almost surely, 2^21042450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21042450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34372800).

21042450 is an abundant number, since it is smaller than the sum of its proper divisors (47703150).

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

21042450 is a wasteful number, since it uses less digits than its factorization.

21042450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 143 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21042450 is about 4587.2050313889. The cubic root of 21042450 is about 276.0781914567.

Adding to 21042450 its reverse (5424012), we get a palindrome (26466462).

It can be divided in two parts, 2104 and 2450, that added together give a palindrome (4554).

The spelling of 21042450 in words is "twenty-one million, forty-two thousand, four hundred fifty".