21315450 has 96 divisors (see below), whose sum is σ = 60371136. Its totient is φ = 4930560.

The previous prime is 21315443. The next prime is 21315451. The reversal of 21315450 is 5451312.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21315451) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32829 + ... + 33471.

It is an arithmetic number, because the mean of its divisors is an integer number (628866).

Almost surely, 2^21315450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21315450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30185568).

21315450 is an abundant number, since it is smaller than the sum of its proper divisors (39055686).

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

21315450 is a wasteful number, since it uses less digits than its factorization.

21315450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688 (or 683 counting only the distinct ones).

The product of its (nonzero) digits is 600, while the sum is 21.

The square root of 21315450 is about 4616.8658200125. The cubic root of 21315450 is about 277.2669905078.

Adding to 21315450 its reverse (5451312), we get a palindrome (26766762).

The spelling of 21315450 in words is "twenty-one million, three hundred fifteen thousand, four hundred fifty".