21540239233 has 2 divisors, whose sum is σ = 21540239234. Its totient is φ = 21540239232.

The previous prime is 21540239213. The next prime is 21540239293. The reversal of 21540239233 is 33293204512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15566804289 + 5973434944 = 124767^2 + 77288^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21540239233 is a prime.

It is not a weakly prime, because it can be changed into another prime (21540239213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10770119616 + 10770119617.

It is an arithmetic number, because the mean of its divisors is an integer number (10770119617).

Almost surely, 2^21540239233 is an apocalyptic number.

It is an amenable number.

21540239233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21540239233 is an equidigital number, since it uses as much as digits as its factorization.

21540239233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 38880, while the sum is 34.

The spelling of 21540239233 in words is "twenty-one billion, five hundred forty million, two hundred thirty-nine thousand, two hundred thirty-three".