1897236661 has 2 divisors, whose sum is σ = 1897236662. Its totient is φ = 1897236660.

The previous prime is 1897236623. The next prime is 1897236721. The reversal of 1897236661 is 1666327981.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1832353636 + 64883025 = 42806^2 + 8055^2 .

It is a cyclic number.

It is not a de Polignac number, because 1897236661 - 2⁹ = 1897236149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1897246661) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 948618330 + 948618331.

It is an arithmetic number, because the mean of its divisors is an integer number (948618331).

Almost surely, 2^1897236661 is an apocalyptic number.

It is an amenable number.

1897236661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1897236661 is an equidigital number, since it uses as much as digits as its factorization.

1897236661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 653184, while the sum is 49.

The square root of 1897236661 is about 43557.2802296011. The cubic root of 1897236661 is about 1237.9615878443.

The spelling of 1897236661 in words is "one billion, eight hundred ninety-seven million, two hundred thirty-six thousand, six hundred sixty-one".