15661556661061 has 8 divisors (see below), whose sum is σ = 15714363843864. Its totient is φ = 15608797163520.

The previous prime is 15661556660993. The next prime is 15661556661071. The reversal of 15661556661061 is 16016665516651.

It can be written as a sum of positive squares in 4 ways, for example, as 2100198030436 + 13561358630625 = 1449206^2 + 3682575^2 .

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 15661556661061 - 2¹³ = 15661556652869 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 15661556660993 and 15661556661011.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (15661556661071) 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, 11263276 + ... + 12577141.

It is an arithmetic number, because the mean of its divisors is an integer number (1964295480483).

Almost surely, 2^{15661556661061} is an apocalyptic number.

It is an amenable number.

15661556661061 is a deficient number, since it is larger than the sum of its proper divisors (52807182803).

15661556661061 is a wasteful number, since it uses less digits than its factorization.

15661556661061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23842631.

The product of its (nonzero) digits is 5832000, while the sum is 55.

The spelling of 15661556661061 in words is "fifteen trillion, six hundred sixty-one billion, five hundred fifty-six million, six hundred sixty-one thousand, sixty-one".