21403653 has 16 divisors (see below), whose sum is σ = 29729280. Its totient is φ = 13680576.

The previous prime is 21403643. The next prime is 21403667. The reversal of 21403653 is 35630412.

It is a happy number.

It is not a de Polignac number, because 21403653 - 2⁵ = 21403621 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21403643) 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, 12876 + ... + 14442.

It is an arithmetic number, because the mean of its divisors is an integer number (1858080).

Almost surely, 2^21403653 is an apocalyptic number.

It is an amenable number.

21403653 is a deficient number, since it is larger than the sum of its proper divisors (8325627).

21403653 is a wasteful number, since it uses less digits than its factorization.

21403653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1756.

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

The square root of 21403653 is about 4626.4082180456. The cubic root of 21403653 is about 277.6489063662.

The spelling of 21403653 in words is "twenty-one million, four hundred three thousand, six hundred fifty-three".