661215755 has 8 divisors (see below), whose sum is σ = 794800512. Its totient is φ = 528078208.

The previous prime is 661215671. The next prime is 661215767. The reversal of 661215755 is 557512166.

661215755 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 661215755 - 2²⁴ = 644438539 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 108539 + ... + 114468.

It is an arithmetic number, because the mean of its divisors is an integer number (99350064).

Almost surely, 2^661215755 is an apocalyptic number.

661215755 is a deficient number, since it is larger than the sum of its proper divisors (133584757).

661215755 is a wasteful number, since it uses less digits than its factorization.

661215755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223605.

The product of its digits is 63000, while the sum is 38.

The square root of 661215755 is about 25714.1158704708. The cubic root of 661215755 is about 871.1930410738.

The spelling of 661215755 in words is "six hundred sixty-one million, two hundred fifteen thousand, seven hundred fifty-five".