16220745661 has 4 divisors (see below), whose sum is σ = 16256240092. Its totient is φ = 16185251232.

The previous prime is 16220745587. The next prime is 16220745677. The reversal of 16220745661 is 16654702261.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16654702261 = 107 ⋅155651423.

It can be written as a sum of positive squares in 2 ways, for example, as 15161243161 + 1059502500 = 123131^2 + 32550^2 .

It is a cyclic number.

It is not a de Polignac number, because 16220745661 - 2²⁹ = 15683874749 is a prime.

It is a super-2 number, since 2×16220745661² (a number of 21 digits) contains 22 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 (16220743661) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 17746530 + ... + 17747443.

It is an arithmetic number, because the mean of its divisors is an integer number (4064060023).

Almost surely, 2^16220745661 is an apocalyptic number.

It is an amenable number.

16220745661 is a deficient number, since it is larger than the sum of its proper divisors (35494431).

16220745661 is an equidigital number, since it uses as much as digits as its factorization.

16220745661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35494430.

The product of its (nonzero) digits is 120960, while the sum is 40.

The spelling of 16220745661 in words is "sixteen billion, two hundred twenty million, seven hundred forty-five thousand, six hundred sixty-one".