1661065561654 has 4 divisors (see below), whose sum is σ = 2491598342484. Its totient is φ = 830532780826.

The previous prime is 1661065561627. The next prime is 1661065561663. The reversal of 1661065561654 is 4561655601661.

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

It is a super-2 number, since 2×1661065561654² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 415266390412 + ... + 415266390415.

It is an arithmetic number, because the mean of its divisors is an integer number (622899585621).

Almost surely, 2^{1661065561654} is an apocalyptic number.

1661065561654 is a deficient number, since it is larger than the sum of its proper divisors (830532780830).

1661065561654 is an equidigital number, since it uses as much as digits as its factorization.

1661065561654 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 830532780829.

The product of its (nonzero) digits is 3888000, while the sum is 52.

The spelling of 1661065561654 in words is "one trillion, six hundred sixty-one billion, sixty-five million, five hundred sixty-one thousand, six hundred fifty-four".