1661521044642 has 64 divisors (see below), whose sum is σ = 3461413824000. Its totient is φ = 531259561728.

The previous prime is 1661521044593. The next prime is 1661521044647. The reversal of 1661521044642 is 2464401251661.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 1661521044594 and 1661521044603.

It is not an unprimeable number, because it can be changed into a prime (1661521044647) 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 31 ways as a sum of consecutive naturals, for example, 15304909 + ... + 15413087.

It is an arithmetic number, because the mean of its divisors is an integer number (54084591000).

Almost surely, 2^{1661521044642} is an apocalyptic number.

1661521044642 is an abundant number, since it is smaller than the sum of its proper divisors (1799892779358).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1661521044642 is a wasteful number, since it uses less digits than its factorization.

1661521044642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109295.

The product of its (nonzero) digits is 276480, while the sum is 42.

The spelling of 1661521044642 in words is "one trillion, six hundred sixty-one billion, five hundred twenty-one million, forty-four thousand, six hundred forty-two".