1691894857 has 2 divisors, whose sum is σ = 1691894858. Its totient is φ = 1691894856.

The previous prime is 1691894837. The next prime is 1691894909. The reversal of 1691894857 is 7584981961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1379453881 + 312440976 = 37141^2 + 17676^2 .

It is a cyclic number.

It is not a de Polignac number, because 1691894857 - 2¹¹ = 1691892809 is a prime.

It is not a weakly prime, because it can be changed into another prime (1691894837) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845947428 + 845947429.

It is an arithmetic number, because the mean of its divisors is an integer number (845947429).

Almost surely, 2^1691894857 is an apocalyptic number.

It is an amenable number.

1691894857 is a deficient number, since it is larger than the sum of its proper divisors (1).

1691894857 is an equidigital number, since it uses as much as digits as its factorization.

1691894857 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4354560, while the sum is 58.

The square root of 1691894857 is about 41132.6495256505. The cubic root of 1691894857 is about 1191.5834338681.

The spelling of 1691894857 in words is "one billion, six hundred ninety-one million, eight hundred ninety-four thousand, eight hundred fifty-seven".