20197531 has 2 divisors, whose sum is σ = 20197532. Its totient is φ = 20197530.

The previous prime is 20197511. The next prime is 20197549. The reversal of 20197531 is 13579102.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20197531 - 2¹⁵ = 20164763 is a prime.

It is a super-2 number, since 2×20197531² = 815880516991922, which contains 22 as substring.

It is a Chen prime.

It is equal to p_1282366 and since 20197531 and 1282366 have the same sum of digits, it is a Honaker prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20197531.

It is not a weakly prime, because it can be changed into another prime (20197501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10098765 + 10098766.

It is an arithmetic number, because the mean of its divisors is an integer number (10098766).

Almost surely, 2^20197531 is an apocalyptic number.

20197531 is a deficient number, since it is larger than the sum of its proper divisors (1).

20197531 is an equidigital number, since it uses as much as digits as its factorization.

20197531 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 20197531 is about 4494.1663298102. The cubic root of 20197531 is about 272.3324717267.

The spelling of 20197531 in words is "twenty million, one hundred ninety-seven thousand, five hundred thirty-one".