1891663601 has 2 divisors, whose sum is σ = 1891663602. Its totient is φ = 1891663600.

The previous prime is 1891663577. The next prime is 1891663607. The reversal of 1891663601 is 1063661981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1350636001 + 541027600 = 36751^2 + 23260^2 .

It is a cyclic number.

It is not a de Polignac number, because 1891663601 - 2⁶ = 1891663537 is a prime.

It is not a weakly prime, because it can be changed into another prime (1891663607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 945831800 + 945831801.

It is an arithmetic number, because the mean of its divisors is an integer number (945831801).

Almost surely, 2^1891663601 is an apocalyptic number.

It is an amenable number.

1891663601 is a deficient number, since it is larger than the sum of its proper divisors (1).

1891663601 is an equidigital number, since it uses as much as digits as its factorization.

1891663601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 41.

The square root of 1891663601 is about 43493.2592593381. The cubic root of 1891663601 is about 1236.7482441066.

The spelling of 1891663601 in words is "one billion, eight hundred ninety-one million, six hundred sixty-three thousand, six hundred one".