1661100665631 has 8 divisors (see below), whose sum is σ = 2416146422784. Its totient is φ = 1006727676120.

The previous prime is 1661100665611. The next prime is 1661100665663. The reversal of 1661100665631 is 1365660011661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1661100665631 - 2¹⁰ = 1661100664607 is a prime.

It is a super-2 number, since 2×1661100665631² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661100665611) 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, 25168191871 + ... + 25168191936.

It is an arithmetic number, because the mean of its divisors is an integer number (302018302848).

Almost surely, 2^{1661100665631} is an apocalyptic number.

1661100665631 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

1661100665631 is a deficient number, since it is larger than the sum of its proper divisors (755045757153).

1661100665631 is a wasteful number, since it uses less digits than its factorization.

1661100665631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50336383821.

The product of its (nonzero) digits is 116640, while the sum is 42.

The spelling of 1661100665631 in words is "one trillion, six hundred sixty-one billion, one hundred million, six hundred sixty-five thousand, six hundred thirty-one".