20523491 has 2 divisors, whose sum is σ = 20523492. Its totient is φ = 20523490.

The previous prime is 20523479. The next prime is 20523497. The reversal of 20523491 is 19432502.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20523491 - 2¹⁴ = 20507107 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20523491.

It is not a weakly prime, because it can be changed into another prime (20523497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10261745 + 10261746.

It is an arithmetic number, because the mean of its divisors is an integer number (10261746).

Almost surely, 2^20523491 is an apocalyptic number.

20523491 is a deficient number, since it is larger than the sum of its proper divisors (1).

20523491 is an equidigital number, since it uses as much as digits as its factorization.

20523491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 20523491 is about 4530.2859733134. The cubic root of 20523491 is about 273.7896826747.

Adding to 20523491 its reverse (19432502), we get a palindrome (39955993).

The spelling of 20523491 in words is "twenty million, five hundred twenty-three thousand, four hundred ninety-one".