661551755699 has 8 divisors (see below), whose sum is σ = 690323662080. Its totient is φ = 632780581576.

The previous prime is 661551755663. The next prime is 661551755707. The reversal of 661551755699 is 996557155166.

661551755699 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 661551755699 - 2⁸ = 661551755443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661551755299) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2499872 + ... + 2751810.

It is an arithmetic number, because the mean of its divisors is an integer number (86290457760).

Almost surely, 2^661551755699 is an apocalyptic number.

661551755699 is a deficient number, since it is larger than the sum of its proper divisors (28771906381).

661551755699 is a wasteful number, since it uses less digits than its factorization.

661551755699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366129.

The product of its digits is 76545000, while the sum is 65.

The spelling of 661551755699 in words is "six hundred sixty-one billion, five hundred fifty-one million, seven hundred fifty-five thousand, six hundred ninety-nine".