21731153 has 4 divisors (see below), whose sum is σ = 21743460. Its totient is φ = 21718848.

The previous prime is 21731147. The next prime is 21731161. The reversal of 21731153 is 35113712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 10387729 + 11343424 = 3223^2 + 3368^2 .

It is a cyclic number.

It is not a de Polignac number, because 21731153 - 2⁶ = 21731089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21731123) 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, 2948 + ... + 7221.

It is an arithmetic number, because the mean of its divisors is an integer number (5435865).

Almost surely, 2^21731153 is an apocalyptic number.

It is an amenable number.

21731153 is a deficient number, since it is larger than the sum of its proper divisors (12307).

21731153 is a wasteful number, since it uses less digits than its factorization.

21731153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12306.

The product of its digits is 630, while the sum is 23.

The square root of 21731153 is about 4661.6684781310. The cubic root of 21731153 is about 279.0578581035.

Adding to 21731153 its reverse (35113712), we get a palindrome (56844865).

The spelling of 21731153 in words is "twenty-one million, seven hundred thirty-one thousand, one hundred fifty-three".