661520614643 has 24 divisors (see below), whose sum is σ = 785100830688. Its totient is φ = 555568855296.

The previous prime is 661520614631. The next prime is 661520614669. The reversal of 661520614643 is 346416025166.

It is not a de Polignac number, because 661520614643 - 2⁸ = 661520614387 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661520614594 and 661520614603.

It is not an unprimeable number, because it can be changed into a prime (661520644643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1758155 + ... + 2100987.

It is an arithmetic number, because the mean of its divisors is an integer number (32712534612).

Almost surely, 2^661520614643 is an apocalyptic number.

661520614643 is a deficient number, since it is larger than the sum of its proper divisors (123580216045).

661520614643 is a wasteful number, since it uses less digits than its factorization.

661520614643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343643 (or 343636 counting only the distinct ones).

The product of its (nonzero) digits is 622080, while the sum is 44.

The spelling of 661520614643 in words is "six hundred sixty-one billion, five hundred twenty million, six hundred fourteen thousand, six hundred forty-three".