189909667921 has 2 divisors, whose sum is σ = 189909667922. Its totient is φ = 189909667920.

The previous prime is 189909667897. The next prime is 189909667957. The reversal of 189909667921 is 129766909981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 188932792896 + 976875025 = 434664^2 + 31255^2 .

It is a cyclic number.

It is not a de Polignac number, because 189909667921 - 2¹¹ = 189909665873 is a prime.

It is not a weakly prime, because it can be changed into another prime (189909467921) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 94954833960 + 94954833961.

It is an arithmetic number, because the mean of its divisors is an integer number (94954833961).

Almost surely, 2^189909667921 is an apocalyptic number.

It is an amenable number.

189909667921 is a deficient number, since it is larger than the sum of its proper divisors (1).

189909667921 is an equidigital number, since it uses as much as digits as its factorization.

189909667921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26453952, while the sum is 67.

The spelling of 189909667921 in words is "one hundred eighty-nine billion, nine hundred nine million, six hundred sixty-seven thousand, nine hundred twenty-one".