1663443661 has 4 divisors (see below), whose sum is σ = 1814665824. Its totient is φ = 1512221500.

The previous prime is 1663443643. The next prime is 1663443667.

1663443661 is nontrivially palindromic in base 10.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1663443661 - 2⁷ = 1663443533 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 (1663443667) 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, 75611065 + ... + 75611086.

It is an arithmetic number, because the mean of its divisors is an integer number (453666456).

Almost surely, 2^1663443661 is an apocalyptic number.

1663443661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1663443661 is a deficient number, since it is larger than the sum of its proper divisors (151222163).

1663443661 is a wasteful number, since it uses less digits than its factorization.

1663443661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 151222162.

The product of its digits is 186624, while the sum is 40.

The square root of 1663443661 is about 40785.3363477611. The cubic root of 1663443661 is about 1184.8663491727.

The spelling of 1663443661 in words is "one billion, six hundred sixty-three million, four hundred forty-three thousand, six hundred sixty-one".