661005055 has 4 divisors (see below), whose sum is σ = 793206072. Its totient is φ = 528804040.

The previous prime is 661005013. The next prime is 661005061. The reversal of 661005055 is 550500166.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 661005055 - 2¹³ = 660996863 is a prime.

It is a super-3 number, since 3×661005055³ (a number of 27 digits) contains 333 as substring.

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 3 ways as a sum of consecutive naturals, for example, 66100501 + ... + 66100510.

It is an arithmetic number, because the mean of its divisors is an integer number (198301518).

Almost surely, 2^661005055 is an apocalyptic number.

661005055 is a deficient number, since it is larger than the sum of its proper divisors (132201017).

661005055 is a wasteful number, since it uses less digits than its factorization.

661005055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 132201016.

The product of its (nonzero) digits is 4500, while the sum is 28.

The square root of 661005055 is about 25710.0185725332. The cubic root of 661005055 is about 871.1004944411.

The spelling of 661005055 in words is "six hundred sixty-one million, five thousand, fifty-five".