1661018744447 has 4 divisors (see below), whose sum is σ = 1669715177856. Its totient is φ = 1652322311040.

The previous prime is 1661018744353. The next prime is 1661018744449. The reversal of 1661018744447 is 7444478101661.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 1661018744447 - 2¹⁴ = 1661018728063 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 (1661018744449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4348216418 + ... + 4348216799.

It is an arithmetic number, because the mean of its divisors is an integer number (417428794464).

Almost surely, 2^{1661018744447} is an apocalyptic number.

1661018744447 is a deficient number, since it is larger than the sum of its proper divisors (8696433409).

1661018744447 is an equidigital number, since it uses as much as digits as its factorization.

1661018744447 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8696433408.

The product of its (nonzero) digits is 3612672, while the sum is 53.

The spelling of 1661018744447 in words is "one trillion, six hundred sixty-one billion, eighteen million, seven hundred forty-four thousand, four hundred forty-seven".