21453630 has 32 divisors (see below), whose sum is σ = 56170368. Its totient is φ = 5200800.

The previous prime is 21453623. The next prime is 21453637. The reversal of 21453630 is 3635412.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21453623) and next prime (21453637).

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 21453630.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21453637) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32176 + ... + 32835.

It is an arithmetic number, because the mean of its divisors is an integer number (1755324).

Almost surely, 2^21453630 is an apocalyptic number.

21453630 is an abundant number, since it is smaller than the sum of its proper divisors (34716738).

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

21453630 is a wasteful number, since it uses less digits than its factorization.

21453630 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 65032.

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21453630 is about 4631.8063431020. The cubic root of 21453630 is about 277.8648394953.

It can be divided in two parts, 2145 and 3630, that added together give a palindrome (5775).

The spelling of 21453630 in words is "twenty-one million, four hundred fifty-three thousand, six hundred thirty".