661555554 has 32 divisors (see below), whose sum is σ = 1467866880. Its totient is φ = 197072400.

The previous prime is 661555513. The next prime is 661555571. The reversal of 661555554 is 455555166.

661555554 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-3 number, since 3×661555554³ (a number of 27 digits) contains 333 as substring.

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, 81052 + ... + 88839.

It is an arithmetic number, because the mean of its divisors is an integer number (45870840).

Almost surely, 2^661555554 is an apocalyptic number.

661555554 is an abundant number, since it is smaller than the sum of its proper divisors (806311326).

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

661555554 is a wasteful number, since it uses less digits than its factorization.

661555554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169966.

The product of its digits is 450000, while the sum is 42.

The square root of 661555554 is about 25720.7222682412. The cubic root of 661555554 is about 871.3422509831.

The spelling of 661555554 in words is "six hundred sixty-one million, five hundred fifty-five thousand, five hundred fifty-four".