21535473 has 8 divisors (see below), whose sum is σ = 28749888. Its totient is φ = 14339024.

The previous prime is 21535433. The next prime is 21535477. The reversal of 21535473 is 37453512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21535473 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21535473.

It is not an unprimeable number, because it can be changed into a prime (21535477) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1386 + ... + 6707.

It is an arithmetic number, because the mean of its divisors is an integer number (3593736).

Almost surely, 2^21535473 is an apocalyptic number.

It is an amenable number.

21535473 is a deficient number, since it is larger than the sum of its proper divisors (7214415).

21535473 is an equidigital number, since it uses as much as digits as its factorization.

21535473 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8983.

The product of its digits is 12600, while the sum is 30.

The square root of 21535473 is about 4640.6328232257. The cubic root of 21535473 is about 278.2177313643.

Adding to 21535473 its reverse (37453512), we get a palindrome (58988985).

It can be divided in two parts, 2153 and 5473, that added together give a triangular number (7626 = T₁₂₃).

The spelling of 21535473 in words is "twenty-one million, five hundred thirty-five thousand, four hundred seventy-three".