21111005731 has 2 divisors, whose sum is σ = 21111005732. Its totient is φ = 21111005730.

The previous prime is 21111005717. The next prime is 21111005743. The reversal of 21111005731 is 13750011112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21111005731 - 2¹⁹ = 21110481443 is a prime.

It is a super-2 number, since 2×21111005731² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21111003731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555502865 + 10555502866.

It is an arithmetic number, because the mean of its divisors is an integer number (10555502866).

Almost surely, 2^21111005731 is an apocalyptic number.

21111005731 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111005731 is an equidigital number, since it uses as much as digits as its factorization.

21111005731 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 210, while the sum is 22.

Adding to 21111005731 its reverse (13750011112), we get a palindrome (34861016843).

The spelling of 21111005731 in words is "twenty-one billion, one hundred eleven million, five thousand, seven hundred thirty-one".