661320543004540 has 96 divisors (see below), whose sum is σ = 1462927392057600. Its totient is φ = 250423869749760.

The previous prime is 661320543004531. The next prime is 661320543004547. The reversal of 661320543004540 is 45400345023166.

It is a happy number.

It is a super-2 number, since 2×661320543004540² (a number of 30 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661320543004547) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 3067426627 + ... + 3067642213.

It is an arithmetic number, because the mean of its divisors is an integer number (15238827000600).

Almost surely, 2^{661320543004540} is an apocalyptic number.

It is an amenable number.

661320543004540 is an abundant number, since it is smaller than the sum of its proper divisors (801606849053060).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661320543004540 is a wasteful number, since it uses less digits than its factorization.

661320543004540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221435 (or 221433 counting only the distinct ones).

The product of its (nonzero) digits is 1036800, while the sum is 43.

The spelling of 661320543004540 in words is "six hundred sixty-one trillion, three hundred twenty billion, five hundred forty-three million, four thousand, five hundred forty".