21735243 has 16 divisors (see below), whose sum is σ = 33072160. Its totient is φ = 14097888.

The previous prime is 21735223. The next prime is 21735251. The reversal of 21735243 is 34253712.

It is not a de Polignac number, because 21735243 - 2⁶ = 21735179 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21735223) 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, 9880 + ... + 11877.

It is an arithmetic number, because the mean of its divisors is an integer number (2067010).

Almost surely, 2^21735243 is an apocalyptic number.

21735243 is a deficient number, since it is larger than the sum of its proper divisors (11336917).

21735243 is a wasteful number, since it uses less digits than its factorization.

21735243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21803 (or 21797 counting only the distinct ones).

The product of its digits is 5040, while the sum is 27.

The square root of 21735243 is about 4662.1071416260. The cubic root of 21735243 is about 279.0753640782.

Adding to 21735243 its reverse (34253712), we get a palindrome (55988955).

The spelling of 21735243 in words is "twenty-one million, seven hundred thirty-five thousand, two hundred forty-three".