21051450 has 144 divisors (see below), whose sum is σ = 66620736. Its totient is φ = 4665600.

The previous prime is 21051431. The next prime is 21051451. The reversal of 21051450 is 5415012.

21051450 is a `hidden beast` number, since 210 + 5 + 1 + 450 = 666.

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 (21051451) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 129069 + ... + 129231.

It is an arithmetic number, because the mean of its divisors is an integer number (462644).

Almost surely, 2^21051450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21051450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33310368).

21051450 is an abundant number, since it is smaller than the sum of its proper divisors (45569286).

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

21051450 is a wasteful number, since it uses less digits than its factorization.

21051450 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 229 (or 221 counting only the distinct ones).

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

The square root of 21051450 is about 4588.1859160239. The cubic root of 21051450 is about 276.1175460243.

Adding to 21051450 its reverse (5415012), we get a palindrome (26466462).

The spelling of 21051450 in words is "twenty-one million, fifty-one thousand, four hundred fifty".