21161131 has 2 divisors, whose sum is σ = 21161132. Its totient is φ = 21161130.

The previous prime is 21161113. The next prime is 21161137. The reversal of 21161131 is 13116112.

Together with previous prime (21161113) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21161131 is a prime.

It is a super-2 number, since 2×21161131² = 895586930398322, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21161137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10580565 + 10580566.

It is an arithmetic number, because the mean of its divisors is an integer number (10580566).

Almost surely, 2^21161131 is an apocalyptic number.

21161131 is a deficient number, since it is larger than the sum of its proper divisors (1).

21161131 is an equidigital number, since it uses as much as digits as its factorization.

21161131 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36, while the sum is 16.

The square root of 21161131 is about 4600.1229331399. The cubic root of 21161131 is about 276.5962526246.

Adding to 21161131 its reverse (13116112), we get a palindrome (34277243).

The spelling of 21161131 in words is "twenty-one million, one hundred sixty-one thousand, one hundred thirty-one".