21431153 has 4 divisors (see below), whose sum is σ = 21440628. Its totient is φ = 21421680.

The previous prime is 21431149. The next prime is 21431161. The reversal of 21431153 is 35113412.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11235904 + 10195249 = 3352^2 + 3193^2 .

It is a cyclic number.

It is not a de Polignac number, because 21431153 - 2² = 21431149 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21431173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 863 + ... + 6603.

It is an arithmetic number, because the mean of its divisors is an integer number (5360157).

Almost surely, 2^21431153 is an apocalyptic number.

It is an amenable number.

21431153 is a deficient number, since it is larger than the sum of its proper divisors (9475).

21431153 is an equidigital number, since it uses as much as digits as its factorization.

21431153 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9474.

The product of its digits is 360, while the sum is 20.

The square root of 21431153 is about 4629.3793320487. The cubic root of 21431153 is about 277.7677657843.

Adding to 21431153 its reverse (35113412), we get a palindrome (56544565).

The spelling of 21431153 in words is "twenty-one million, four hundred thirty-one thousand, one hundred fifty-three".