21153440263 has 4 divisors (see below), whose sum is σ = 21469163320. Its totient is φ = 20837717208.

The previous prime is 21153440227. The next prime is 21153440267. The reversal of 21153440263 is 36204435112.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21153440263 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153440267) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 157861428 + ... + 157861561.

It is an arithmetic number, because the mean of its divisors is an integer number (5367290830).

Almost surely, 2^21153440263 is an apocalyptic number.

21153440263 is a deficient number, since it is larger than the sum of its proper divisors (315723057).

21153440263 is an equidigital number, since it uses as much as digits as its factorization.

21153440263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 315723056.

The product of its (nonzero) digits is 17280, while the sum is 31.

Adding to 21153440263 its reverse (36204435112), we get a palindrome (57357875375).

The spelling of 21153440263 in words is "twenty-one billion, one hundred fifty-three million, four hundred forty thousand, two hundred sixty-three".