661705553 has 4 divisors (see below), whose sum is σ = 661924788. Its totient is φ = 661486320.

The previous prime is 661705549. The next prime is 661705559. The reversal of 661705553 is 355507166.

661705553 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 415466689 + 246238864 = 20383^2 + 15692^2 .

It is a cyclic number.

It is not a de Polignac number, because 661705553 - 2² = 661705549 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661705559) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105026 + ... + 111147.

It is an arithmetic number, because the mean of its divisors is an integer number (165481197).

Almost surely, 2^661705553 is an apocalyptic number.

It is an amenable number.

661705553 is a deficient number, since it is larger than the sum of its proper divisors (219235).

661705553 is a wasteful number, since it uses less digits than its factorization.

661705553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219234.

The product of its (nonzero) digits is 94500, while the sum is 38.

The square root of 661705553 is about 25723.6380203112. The cubic root of 661705553 is about 871.4081011291.

The spelling of 661705553 in words is "six hundred sixty-one million, seven hundred five thousand, five hundred fifty-three".