661565287929 has 128 divisors (see below), whose sum is σ = 1147695431680. Its totient is φ = 329708620800.

The previous prime is 661565287921. The next prime is 661565287949. The reversal of 661565287929 is 929782565166.

661565287929 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 661565287929 - 2³ = 661565287921 is a prime.

It is a Smith number, since the sum of its digits (66) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 661565287929.

It is not an unprimeable number, because it can be changed into a prime (661565287921) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 48669924 + ... + 48683514.

It is an arithmetic number, because the mean of its divisors is an integer number (8966370560).

Almost surely, 2^661565287929 is an apocalyptic number.

It is an amenable number.

661565287929 is a deficient number, since it is larger than the sum of its proper divisors (486130143751).

661565287929 is a wasteful number, since it uses less digits than its factorization.

661565287929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13791.

The product of its digits is 97977600, while the sum is 66.

The spelling of 661565287929 in words is "six hundred sixty-one billion, five hundred sixty-five million, two hundred eighty-seven thousand, nine hundred twenty-nine".