201912321661 has 2 divisors, whose sum is σ = 201912321662. Its totient is φ = 201912321660.

The previous prime is 201912321629. The next prime is 201912321703. The reversal of 201912321661 is 166123219102.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 123900480025 + 78011841636 = 351995^2 + 279306^2 .

It is a cyclic number.

It is not a de Polignac number, because 201912321661 - 2⁵ = 201912321629 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201912324661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100956160830 + 100956160831.

It is an arithmetic number, because the mean of its divisors is an integer number (100956160831).

Almost surely, 2^201912321661 is an apocalyptic number.

It is an amenable number.

201912321661 is a deficient number, since it is larger than the sum of its proper divisors (1).

201912321661 is an equidigital number, since it uses as much as digits as its factorization.

201912321661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7776, while the sum is 34.

The spelling of 201912321661 in words is "two hundred one billion, nine hundred twelve million, three hundred twenty-one thousand, six hundred sixty-one".