21921450 has 48 divisors (see below), whose sum is σ = 55308960. Its totient is φ = 5744320.

The previous prime is 21921437. The next prime is 21921451. The reversal of 21921450 is 5412912.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21921450.

It is not an unprimeable number, because it can be changed into a prime (21921451) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7612 + ... + 10088.

It is an arithmetic number, because the mean of its divisors is an integer number (1152270).

Almost surely, 2^21921450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21921450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27654480).

21921450 is an abundant number, since it is smaller than the sum of its proper divisors (33387510).

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

21921450 is a wasteful number, since it uses less digits than its factorization.

21921450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2551 (or 2546 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 24.

The square root of 21921450 is about 4682.0348140525. The cubic root of 21921450 is about 279.8700502431.

The spelling of 21921450 in words is "twenty-one million, nine hundred twenty-one thousand, four hundred fifty".