1644231501661 has 8 divisors (see below), whose sum is σ = 1879708417344. Its totient is φ = 1408901261280.

The previous prime is 1644231501569. The next prime is 1644231501707. The reversal of 1644231501661 is 1661051324461.

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 1644231501661 - 2⁷ = 1644231501533 is a prime.

It is a super-3 number, since 3×1644231501661³ (a number of 38 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1644231501061) 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, 36644800 + ... + 36689641.

It is an arithmetic number, because the mean of its divisors is an integer number (234963552168).

Almost surely, 2^{1644231501661} is an apocalyptic number.

It is an amenable number.

1644231501661 is a deficient number, since it is larger than the sum of its proper divisors (235476915683).

1644231501661 is an equidigital number, since it uses as much as digits as its factorization.

1644231501661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73337651.

The product of its (nonzero) digits is 103680, while the sum is 40.

The spelling of 1644231501661 in words is "one trillion, six hundred forty-four billion, two hundred thirty-one million, five hundred one thousand, six hundred sixty-one".