21742653 has 4 divisors (see below), whose sum is σ = 28990208. Its totient is φ = 14495100.

The previous prime is 21742627. The next prime is 21742691. The reversal of 21742653 is 35624712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a de Polignac number, because none of the positive numbers 2^k-21742653 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21742653.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742603) 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 3 ways as a sum of consecutive naturals, for example, 3623773 + ... + 3623778.

It is an arithmetic number, because the mean of its divisors is an integer number (7247552).

Almost surely, 2^21742653 is an apocalyptic number.

It is an amenable number.

21742653 is a deficient number, since it is larger than the sum of its proper divisors (7247555).

21742653 is an equidigital number, since it uses as much as digits as its factorization.

21742653 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7247554.

The product of its digits is 10080, while the sum is 30.

The square root of 21742653 is about 4662.9017789355. The cubic root of 21742653 is about 279.1070746889.

The spelling of 21742653 in words is "twenty-one million, seven hundred forty-two thousand, six hundred fifty-three".