1661610111645 has 16 divisors (see below), whose sum is σ = 2900264922432. Its totient is φ = 805629144960.

The previous prime is 1661610111589. The next prime is 1661610111713. The reversal of 1661610111645 is 5461110161661.

It is not a de Polignac number, because 1661610111645 - 2¹⁹ = 1661609587357 is a prime.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5035181992 + ... + 5035182321.

It is an arithmetic number, because the mean of its divisors is an integer number (181266557652).

Almost surely, 2^{1661610111645} is an apocalyptic number.

1661610111645 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1661610111645 is a deficient number, since it is larger than the sum of its proper divisors (1238654810787).

1661610111645 is a wasteful number, since it uses less digits than its factorization.

1661610111645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10070364332.

The product of its (nonzero) digits is 25920, while the sum is 39.

The spelling of 1661610111645 in words is "one trillion, six hundred sixty-one billion, six hundred ten million, one hundred eleven thousand, six hundred forty-five".