21501450 has 60 divisors (see below), whose sum is σ = 59753430. Its totient is φ = 5732640.

The previous prime is 21501401. The next prime is 21501451. The reversal of 21501450 is 5410512.

21501450 is a `hidden beast` number, since 215 + 0 + 1 + 450 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 8346321 + 13155129 = 2889^2 + 3627^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21501451) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 1396 + ... + 6704.

Almost surely, 2^21501450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21501450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29876715).

21501450 is an abundant number, since it is smaller than the sum of its proper divisors (38251980).

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

21501450 is a wasteful number, since it uses less digits than its factorization.

21501450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5333 (or 5319 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21501450 is about 4636.9656026328. The cubic root of 21501450 is about 278.0711392567.

Adding to 21501450 its reverse (5410512), we get a palindrome (26911962).

It can be divided in two parts, 2150 and 1450, that added together give a square (3600 = 60²).

The spelling of 21501450 in words is "twenty-one million, five hundred one thousand, four hundred fifty".