21404250 has 160 divisors (see below), whose sum is σ = 68859648. Its totient is φ = 4860000.

The previous prime is 21404213. The next prime is 21404263. The reversal of 21404250 is 5240412.

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

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 141675 + ... + 141825.

Almost surely, 2^21404250 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21404250, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34429824).

21404250 is an abundant number, since it is smaller than the sum of its proper divisors (47455398).

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

21404250 is a wasteful number, since it uses less digits than its factorization.

21404250 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 187 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21404250 is about 4626.4727384910. The cubic root of 21404250 is about 277.6514877769.

Adding to 21404250 its reverse (5240412), we get a palindrome (26644662).

The spelling of 21404250 in words is "twenty-one million, four hundred four thousand, two hundred fifty".