21111111031 has 2 divisors, whose sum is σ = 21111111032. Its totient is φ = 21111111030.

The previous prime is 21111111023. The next prime is 21111111059. The reversal of 21111111031 is 13011111112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21111111031 - 2³ = 21111111023 is a prime.

It is a super-2 number, since 2×21111111031² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21111111061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10555555515 + 10555555516.

It is an arithmetic number, because the mean of its divisors is an integer number (10555555516).

Almost surely, 2^21111111031 is an apocalyptic number.

21111111031 is a deficient number, since it is larger than the sum of its proper divisors (1).

21111111031 is an equidigital number, since it uses as much as digits as its factorization.

21111111031 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6, while the sum is 13.

Adding to 21111111031 its reverse (13011111112), we get a palindrome (34122222143).

The spelling of 21111111031 in words is "twenty-one billion, one hundred eleven million, one hundred eleven thousand, thirty-one".