20691131 has 2 divisors, whose sum is σ = 20691132. Its totient is φ = 20691130.

The previous prime is 20691113. The next prime is 20691137. The reversal of 20691131 is 13119602.

It is a happy number.

Together with previous prime (20691113) 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 not a de Polignac number, because 20691131 - 2⁶ = 20691067 is a prime.

It is a super-2 number, since 2×20691131² = 856245804118322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20691097 and 20691106.

It is not a weakly prime, because it can be changed into another prime (20691137) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10345565 + 10345566.

It is an arithmetic number, because the mean of its divisors is an integer number (10345566).

Almost surely, 2^20691131 is an apocalyptic number.

20691131 is a deficient number, since it is larger than the sum of its proper divisors (1).

20691131 is an equidigital number, since it uses as much as digits as its factorization.

20691131 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 20691131 is about 4548.7504877713. The cubic root of 20691131 is about 274.5331185440.

The spelling of 20691131 in words is "twenty million, six hundred ninety-one thousand, one hundred thirty-one".