1661331661 has 8 divisors (see below), whose sum is σ = 1812843648. Its totient is φ = 1509900000.

The previous prime is 1661331641. The next prime is 1661331677.

1661331661 is nontrivially palindromic in base 10.

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 1661331661 - 2⁷ = 1661331533 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661331611) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28236 + ... + 64186.

It is an arithmetic number, because the mean of its divisors is an integer number (226605456).

Almost surely, 2^1661331661 is an apocalyptic number.

1661331661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1661331661 is a deficient number, since it is larger than the sum of its proper divisors (151511987).

1661331661 is a wasteful number, since it uses less digits than its factorization.

1661331661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40163.

The product of its digits is 11664, while the sum is 34.

The square root of 1661331661 is about 40759.4364656824. The cubic root of 1661331661 is about 1184.3646795313.

The spelling of 1661331661 in words is "one billion, six hundred sixty-one million, three hundred thirty-one thousand, six hundred sixty-one".