661611511055 has 16 divisors (see below), whose sum is σ = 866130509088. Its totient is φ = 481160400000.

The previous prime is 661611511049. The next prime is 661611511061. The reversal of 661611511055 is 550115116166.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (661611511049) and next prime (661611511061).

It is not a de Polignac number, because 661611511055 - 2¹⁶ = 661611445519 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2635505 + ... + 2875605.

It is an arithmetic number, because the mean of its divisors is an integer number (54133156818).

Almost surely, 2^661611511055 is an apocalyptic number.

661611511055 is a deficient number, since it is larger than the sum of its proper divisors (204518998033).

661611511055 is a wasteful number, since it uses less digits than its factorization.

661611511055 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290218.

The product of its (nonzero) digits is 27000, while the sum is 38.

The spelling of 661611511055 in words is "six hundred sixty-one billion, six hundred eleven million, five hundred eleven thousand, fifty-five".