661489831015776 has 144 divisors (see below), whose sum is σ = 2149870919099904. Its totient is φ = 188994547913472.

The previous prime is 661489831015771. The next prime is 661489831015823. The reversal of 661489831015776 is 677510138984166.

661489831015776 is a `hidden beast` number, since 6 + 6 + 1 + 4 + 8 + 98 + 310 + 157 + 76 = 666.

661489831015776 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661489831015771) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 150041155 + ... + 154386941.

It is an arithmetic number, because the mean of its divisors is an integer number (14929659160416).

Almost surely, 2^{661489831015776} is an apocalyptic number.

It is an amenable number.

661489831015776 is an abundant number, since it is smaller than the sum of its proper divisors (1488381088084128).

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

661489831015776 is a wasteful number, since it uses less digits than its factorization.

661489831015776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4421313 (or 4421302 counting only the distinct ones).

The product of its (nonzero) digits is 365783040, while the sum is 72.

The spelling of 661489831015776 in words is "six hundred sixty-one trillion, four hundred eighty-nine billion, eight hundred thirty-one million, fifteen thousand, seven hundred seventy-six".