21409450 has 24 divisors (see below), whose sum is σ = 39967308. Its totient is φ = 8532480.

The previous prime is 21409429. The next prime is 21409457. The reversal of 21409450 is 5490412.

It can be written as a sum of positive squares in 6 ways, for example, as 1934881 + 19474569 = 1391^2 + 4413^2 .

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is not an unprimeable number, because it can be changed into a prime (21409457) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17044 + ... + 18256.

Almost surely, 2^21409450 is an apocalyptic number.

21409450 is a deficient number, since it is larger than the sum of its proper divisors (18557858).

21409450 is a wasteful number, since it uses less digits than its factorization.

21409450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1578 (or 1573 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 25.

The square root of 21409450 is about 4627.0346875726. The cubic root of 21409450 is about 277.6739703965.

Adding to 21409450 its reverse (5490412), we get a palindrome (26899862).

The spelling of 21409450 in words is "twenty-one million, four hundred nine thousand, four hundred fifty".