661550655 has 16 divisors (see below), whose sum is σ = 1066564224. Its totient is φ = 350132640.

The previous prime is 661550653. The next prime is 661550671. The reversal of 661550655 is 556055166.

It is not a de Polignac number, because 661550655 - 2¹ = 661550653 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661550651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 166369 + ... + 170298.

It is an arithmetic number, because the mean of its divisors is an integer number (66660264).

Almost surely, 2^661550655 is an apocalyptic number.

661550655 is a deficient number, since it is larger than the sum of its proper divisors (405013569).

661550655 is a wasteful number, since it uses less digits than its factorization.

661550655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336806.

The product of its (nonzero) digits is 135000, while the sum is 39.

The square root of 661550655 is about 25720.6270335698. The cubic root of 661550655 is about 871.3401001352.

The spelling of 661550655 in words is "six hundred sixty-one million, five hundred fifty thousand, six hundred fifty-five".