21606450 has 48 divisors (see below), whose sum is σ = 55442880. Its totient is φ = 5561920.

The previous prime is 21606443. The next prime is 21606469. The reversal of 21606450 is 5460612.

It is a self number, because there is not a number n which added to its sum of digits gives 21606450.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1867 + ... + 6833.

It is an arithmetic number, because the mean of its divisors is an integer number (1155060).

Almost surely, 2^21606450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21606450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27721440).

21606450 is an abundant number, since it is smaller than the sum of its proper divisors (33836430).

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

21606450 is a wasteful number, since it uses less digits than its factorization.

21606450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5011 (or 5006 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 21606450 is about 4648.2738731706. The cubic root of 21606450 is about 278.5230478580.

The spelling of 21606450 in words is "twenty-one million, six hundred six thousand, four hundred fifty".