661455630263 has 4 divisors (see below), whose sum is σ = 670516666368. Its totient is φ = 652394594160.

The previous prime is 661455630259. The next prime is 661455630299. The reversal of 661455630263 is 362036554166.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 661455630263 - 2² = 661455630259 is a prime.

It is a super-2 number, since 2×661455630263² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661455630203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4530517943 + ... + 4530518088.

It is an arithmetic number, because the mean of its divisors is an integer number (167629166592).

Almost surely, 2^661455630263 is an apocalyptic number.

661455630263 is a deficient number, since it is larger than the sum of its proper divisors (9061036105).

661455630263 is an equidigital number, since it uses as much as digits as its factorization.

661455630263 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9061036104.

The product of its (nonzero) digits is 2332800, while the sum is 47.

The spelling of 661455630263 in words is "six hundred sixty-one billion, four hundred fifty-five million, six hundred thirty thousand, two hundred sixty-three".