661711553 has 4 divisors (see below), whose sum is σ = 700635780. Its totient is φ = 622787328.

The previous prime is 661711513. The next prime is 661711559. The reversal of 661711553 is 355117166.

661711553 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 473802289 + 187909264 = 21767^2 + 13708^2 .

It is a cyclic number.

It is not a de Polignac number, because 661711553 - 2¹⁶ = 661646017 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661711559) 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, 19462088 + ... + 19462121.

It is an arithmetic number, because the mean of its divisors is an integer number (175158945).

Almost surely, 2^661711553 is an apocalyptic number.

It is an amenable number.

661711553 is a deficient number, since it is larger than the sum of its proper divisors (38924227).

661711553 is a wasteful number, since it uses less digits than its factorization.

661711553 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38924226.

The product of its digits is 18900, while the sum is 35.

The square root of 661711553 is about 25723.7546442972. The cubic root of 661711553 is about 871.4107349455.

The spelling of 661711553 in words is "six hundred sixty-one million, seven hundred eleven thousand, five hundred fifty-three".