21311017433 has 4 divisors (see below), whose sum is σ = 21830798388. Its totient is φ = 20791236480.

The previous prime is 21311017373. The next prime is 21311017489. The reversal of 21311017433 is 33471011312.

It is a happy number.

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 9063611209 + 12247406224 = 95203^2 + 110668^2 .

It is a cyclic number.

It is not a de Polignac number, because 21311017433 - 2¹² = 21311013337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311017493) 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, 259890416 + ... + 259890497.

It is an arithmetic number, because the mean of its divisors is an integer number (5457699597).

Almost surely, 2^21311017433 is an apocalyptic number.

It is an amenable number.

21311017433 is a deficient number, since it is larger than the sum of its proper divisors (519780955).

21311017433 is an equidigital number, since it uses as much as digits as its factorization.

21311017433 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 519780954.

The product of its (nonzero) digits is 1512, while the sum is 26.

Adding to 21311017433 its reverse (33471011312), we get a palindrome (54782028745).

The spelling of 21311017433 in words is "twenty-one billion, three hundred eleven million, seventeen thousand, four hundred thirty-three".