3556220155661 has 2 divisors, whose sum is σ = 3556220155662. Its totient is φ = 3556220155660.

The previous prime is 3556220155633. The next prime is 3556220155673. The reversal of 3556220155661 is 1665510226553.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3503747548900 + 52472606761 = 1871830^2 + 229069^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-3556220155661 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3556220158661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1778110077830 + 1778110077831.

It is an arithmetic number, because the mean of its divisors is an integer number (1778110077831).

Almost surely, 2^{3556220155661} is an apocalyptic number.

It is an amenable number.

3556220155661 is a deficient number, since it is larger than the sum of its proper divisors (1).

3556220155661 is an equidigital number, since it uses as much as digits as its factorization.

3556220155661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1620000, while the sum is 47.

The spelling of 3556220155661 in words is "three trillion, five hundred fifty-six billion, two hundred twenty million, one hundred fifty-five thousand, six hundred sixty-one".