20891131 has 2 divisors, whose sum is σ = 20891132. Its totient is φ = 20891130.

The previous prime is 20891093. The next prime is 20891149. The reversal of 20891131 is 13119802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20891131 - 2⁹ = 20890619 is a prime.

It is a super-2 number, since 2×20891131² = 872878708918322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 20891096 and 20891105.

It is not a weakly prime, because it can be changed into another prime (20891161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10445565 + 10445566.

It is an arithmetic number, because the mean of its divisors is an integer number (10445566).

Almost surely, 2^20891131 is an apocalyptic number.

20891131 is a deficient number, since it is larger than the sum of its proper divisors (1).

20891131 is an equidigital number, since it uses as much as digits as its factorization.

20891131 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 25.

The square root of 20891131 is about 4570.6816778244. The cubic root of 20891131 is about 275.4148273771.

The spelling of 20891131 in words is "twenty million, eight hundred ninety-one thousand, one hundred thirty-one".