661125655 has 8 divisors (see below), whose sum is σ = 794152512. Its totient is φ = 528366048.

The previous prime is 661125613. The next prime is 661125677. The reversal of 661125655 is 556521166.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 661125655 - 2²³ = 652737047 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 61327 + ... + 71296.

It is an arithmetic number, because the mean of its divisors is an integer number (99269064).

Almost surely, 2^661125655 is an apocalyptic number.

661125655 is a deficient number, since it is larger than the sum of its proper divisors (133026857).

661125655 is a wasteful number, since it uses less digits than its factorization.

661125655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133625.

The product of its digits is 54000, while the sum is 37.

The square root of 661125655 is about 25712.3638547684. The cubic root of 661125655 is about 871.1534684844.

It can be divided in two parts, 66 and 1125655, that added together give a square (1125721 = 1061²).

The spelling of 661125655 in words is "six hundred sixty-one million, one hundred twenty-five thousand, six hundred fifty-five".