1243018661 has 2 divisors, whose sum is σ = 1243018662. Its totient is φ = 1243018660.

The previous prime is 1243018649. The next prime is 1243018691. The reversal of 1243018661 is 1668103421.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 875568100 + 367450561 = 29590^2 + 19169^2 .

It is a cyclic number.

It is not a de Polignac number, because 1243018661 - 2¹⁰ = 1243017637 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1243018691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 621509330 + 621509331.

It is an arithmetic number, because the mean of its divisors is an integer number (621509331).

Almost surely, 2^1243018661 is an apocalyptic number.

It is an amenable number.

1243018661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1243018661 is an equidigital number, since it uses as much as digits as its factorization.

1243018661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 32.

The square root of 1243018661 is about 35256.4697750640. The cubic root of 1243018661 is about 1075.2081546802.

The spelling of 1243018661 in words is "one billion, two hundred forty-three million, eighteen thousand, six hundred sixty-one".