15551505055661 has 4 divisors (see below), whose sum is σ = 15616034122524. Its totient is φ = 15486975988800.

The previous prime is 15551505055649. The next prime is 15551505055699. The reversal of 15551505055661 is 16655050515551.

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

It can be written as a sum of positive squares in 2 ways, for example, as 10780098289636 + 4771406766025 = 3283306^2 + 2184355^2 .

It is a cyclic number.

It is not a de Polignac number, because 15551505055661 - 2³⁴ = 15534325186477 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 (15551505055621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 32264533070 + ... + 32264533551.

It is an arithmetic number, because the mean of its divisors is an integer number (3904008530631).

Almost surely, 2^{15551505055661} is an apocalyptic number.

It is an amenable number.

15551505055661 is a deficient number, since it is larger than the sum of its proper divisors (64529066863).

15551505055661 is an equidigital number, since it uses as much as digits as its factorization.

15551505055661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64529066862.

The product of its (nonzero) digits is 2812500, while the sum is 50.

The spelling of 15551505055661 in words is "fifteen trillion, five hundred fifty-one billion, five hundred five million, fifty-five thousand, six hundred sixty-one".