1661515015661 has 8 divisors (see below), whose sum is σ = 1752740641920. Its totient is φ = 1570667136192.

The previous prime is 1661515015651. The next prime is 1661515015663. The reversal of 1661515015661 is 1665105151661.

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 1661515015661 - 2⁶ = 1661515015597 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661515015663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 94427660 + ... + 94445253.

It is an arithmetic number, because the mean of its divisors is an integer number (219092580240).

Almost surely, 2^{1661515015661} is an apocalyptic number.

It is an amenable number.

1661515015661 is a deficient number, since it is larger than the sum of its proper divisors (91225626259).

1661515015661 is a wasteful number, since it uses less digits than its factorization.

1661515015661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 188873395.

The product of its (nonzero) digits is 162000, while the sum is 44.

The spelling of 1661515015661 in words is "one trillion, six hundred sixty-one billion, five hundred fifteen million, fifteen thousand, six hundred sixty-one".