21450040 has 64 divisors (see below), whose sum is σ = 50220000. Its totient is φ = 8240640.

The previous prime is 21450029. The next prime is 21450061. The reversal of 21450040 is 4005412.

It is a junction number, because it is equal to n+sod(n) for n = 21449996 and 21450023.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 143886 + ... + 144034.

Almost surely, 2^21450040 is an apocalyptic number.

21450040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21450040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25110000).

21450040 is an abundant number, since it is smaller than the sum of its proper divisors (28769960).

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

21450040 is a wasteful number, since it uses less digits than its factorization.

21450040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 280 (or 276 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 16.

The square root of 21450040 is about 4631.4187890969. The cubic root of 21450040 is about 277.8493395477.

Adding to 21450040 its reverse (4005412), we get a palindrome (25455452).

The spelling of 21450040 in words is "twenty-one million, four hundred fifty thousand, forty".