21520440311 has 2 divisors, whose sum is σ = 21520440312. Its totient is φ = 21520440310.

The previous prime is 21520440289. The next prime is 21520440317. The reversal of 21520440311 is 11304402512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21520440311 - 2¹⁴ = 21520423927 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21520440317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10760220155 + 10760220156.

It is an arithmetic number, because the mean of its divisors is an integer number (10760220156).

Almost surely, 2^21520440311 is an apocalyptic number.

21520440311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21520440311 is an equidigital number, since it uses as much as digits as its factorization.

21520440311 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 960, while the sum is 23.

Adding to 21520440311 its reverse (11304402512), we get a palindrome (32824842823).

The spelling of 21520440311 in words is "twenty-one billion, five hundred twenty million, four hundred forty thousand, three hundred eleven".