20531742991 has 2 divisors, whose sum is σ = 20531742992. Its totient is φ = 20531742990.

The previous prime is 20531742983. The next prime is 20531743039. The reversal of 20531742991 is 19924713502.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20531742991 - 2³ = 20531742983 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20531742961) 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, 10265871495 + 10265871496.

It is an arithmetic number, because the mean of its divisors is an integer number (10265871496).

Almost surely, 2^20531742991 is an apocalyptic number.

20531742991 is a deficient number, since it is larger than the sum of its proper divisors (1).

20531742991 is an equidigital number, since it uses as much as digits as its factorization.

20531742991 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 43.

The spelling of 20531742991 in words is "twenty billion, five hundred thirty-one million, seven hundred forty-two thousand, nine hundred ninety-one".