661320543004531 has 2 divisors, whose sum is σ = 661320543004532. Its totient is φ = 661320543004530.

The previous prime is 661320543004501. The next prime is 661320543004547. The reversal of 661320543004531 is 135400345023166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661320543004531 - 2³⁹ = 660770787190643 is a prime.

It is a super-2 number, since 2×661320543004531² (a number of 30 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661320543004501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330660271502265 + 330660271502266.

It is an arithmetic number, because the mean of its divisors is an integer number (330660271502266).

Almost surely, 2^{661320543004531} is an apocalyptic number.

661320543004531 is a deficient number, since it is larger than the sum of its proper divisors (1).

661320543004531 is an equidigital number, since it uses as much as digits as its factorization.

661320543004531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 777600, while the sum is 43.

Adding to 661320543004531 its reverse (135400345023166), we get a palindrome (796720888027697).

The spelling of 661320543004531 in words is "six hundred sixty-one trillion, three hundred twenty billion, five hundred forty-three million, four thousand, five hundred thirty-one".