661056551 has 8 divisors (see below), whose sum is σ = 681320640. Its totient is φ = 641050848.

The previous prime is 661056499. The next prime is 661056601. The reversal of 661056551 is 155650166.

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 661056551 - 2²² = 656862247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661056251) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 59396 + ... + 69641.

It is an arithmetic number, because the mean of its divisors is an integer number (85165080).

Almost surely, 2^661056551 is an apocalyptic number.

661056551 is a deficient number, since it is larger than the sum of its proper divisors (20264089).

661056551 is a wasteful number, since it uses less digits than its factorization.

661056551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129193.

The product of its (nonzero) digits is 27000, while the sum is 35.

The square root of 661056551 is about 25711.0200303294. The cubic root of 661056551 is about 871.1231150580.

The spelling of 661056551 in words is "six hundred sixty-one million, fifty-six thousand, five hundred fifty-one".